797 F.2d 1222 (1986)2
United States Court of Appeals, Third Circuit.
Argued March 3, 1986.
Decided August 4, 1986.
  Joel S. Goldhammer (argued), Seidel, Gonda, Goldhammer & Abbott, Philadelphia, Pa., Irwin S. Rubin, Rubin, Glickman & Steinberg, Souderton, Pa., for appellee Whelan Associates, Inc.5
Michael J. Mangan (argued), Robert S. Bramson, Ronald E. Karam, Schnader, Harrison, Segal & Lewis, Philadelphia, Pa., for appellants Jaslow Dental Laboratory, Inc. and Dentcom, Inc.6
Ronald J. Palenski, Morton David Goldberg, Richard Dannay, Jo Recht, ADAPSO Office of the Gen. Counsel, Arlington, Va., for amicus curiae ADAPSO, The Computer Software and Services Industry Association, Inc.7
Before GIBBONS, BECKER, and ROSENN, Circuit Judges.8
This appeal involves a computer program for the operation of a dental laboratory, and calls upon us to apply the principles underlying our venerable copyright laws to the relatively new field of computer technology to determine the scope of copyright protection of a computer program. More particularly, in this case of first impression in the courts of appeals, we must determine whether the structure (or sequence and organization) of a computer program is protectible by copyright, or whether the protection of the copyright law extends only as far as the literal computer code. The district court found that the copyright  law covered these non-literal elements of the program, and we agree. This conclusion in turn requires us to consider whether there was sufficient evidence of substantial similarity between the structures of the two programs at issue in this case to uphold the district court's finding of copyright infringement. Because we find that there was enough evidence, we affirm.11
Appellant Jaslow Dental Laboratory, Inc. ("Jaslow Lab") is a Pennsylvania corporation in the business of manufacturing dental prosthetics and devices. Appellant Dentcom, Inc. ("Dentcom") is a Pennsylvania corporation in the business of developing and marketing computer programs for use by dental laboratories. Dentcom was formed out of the events that gave rise to this suit, and its history will be recounted below. Individual appellants Edward Jaslow and his son Rand Jaslow are officers and shareholders in both Jaslow Lab and Dentcom. Appellants were defendants in the district court. Plaintiff-appellee Whelan Associates, Inc. ("Whelan Associates") is also a Pennsylvania corporation, engaged in the business of developing and marketing custom computer programs.13
Jaslow Lab, like any other small- or medium-sized business of moderate complexity, has significant bookkeeping and administrative tasks. Each order for equipment must be registered and processed; inventory must be maintained; customer lists must be continually updated; invoicing, billing, and accounts receivable, must be dealt with. While many of these functions are common to all businesses, the nature of the dental prosthetics business apparently requires some variations on the basic theme.14
Although Rand Jaslow had not had extensive experience with computers, he believed that the business operations of Jaslow Lab could be made more efficient if they were computerized. In early 1978, he therefore bought a small personal computer and tried to teach himself how to program it so that it would be of use to Jaslow Lab. Although he wrote a program for the computer, he was ultimately not successful, limited by both his lack of expertise and the relatively small capacity of his particular computer.15
A few months later, stymied by his own lack of success but still confident that Jaslow Lab would profit from computerization, Rand Jaslow hired the Strohl Systems Group, Inc. ("Strohl"), a small corporation that developed custom-made software to develop a program that would run on Jaslow Lab's new IBM Series One computer and take care of the Lab's business needs. Jaslow Lab and Strohl entered into an agreement providing that Strohl would design a system for Jaslow Lab's needs and that after Strohl had installed the system Strohl could market it to other dental laboratories. Jaslow Lab would receive a 10% royalty on all such sales. The person at Strohl responsible for the Jaslow Lab account was Elaine Whelan, an experienced programmer who was an officer and half-owner of Strohl.16
Ms. Whelan's first step was to visit Jaslow Lab and interview Rand Jaslow and others to learn how the laboratory worked and what its needs were. She also visited other dental laboratories and interviewed people there, so that she would better understand  the layout, workflow, and administration of dental laboratories generally. After this education into the ways of dental laboratories, and Jaslow Lab, in particular, Ms. Whelan wrote a program called Dentalab for Jaslow Lab. Dentalab was written in a computer language known as EDL (Event Driven Language), so that it would work with IBM Series One machines. The program was completed and was operative at Jaslow Lab around March 1979.17
Presumably with an eye towards exploiting the economic potential of the Dentalab program, Ms. Whelan left Strohl in November, 1979, to form her own business, Whelan Associates, Inc., which acquired Strohl's interest in the Dentalab program. Shortly thereafter, Whelan Associates entered into negotiations with Jaslow Lab for Jaslow Lab to be Whelan Associates' sales representative for the Dentalab program. Whelan Associates and Jaslow Lab entered into an agreement on July 30, 1980, according to which Jaslow Lab agreed to use its "best efforts and to act diligently in the marketing of the Dentalab package," and Whelan Associates agreed to "use its best efforts and to act diligently to improve and augment the previously successfully designed Dentalab package." App. at 1779. The agreement stated that Jaslow Lab would receive 35% of the gross price of any programs sold and 5% of the price of any modifications to the programs. The agreement was for one year and was then terminable by either party on thirty days' notice.18
The parties' business relationship worked successfully for two years. During this time, as Rand Jaslow became more familiar with computer programming, he realized that because Dentalab was written in EDL it could not be used on computers that many of the smaller dental prosthetics firms were using, for which EDL had not been implemented. Sensing that there might be a market for a program that served essentially the same function as Dentalab but that could be used more widely, Rand Jaslow began in May or June of 1982 to develop in his spare time a program in the BASIC language for such computers. That program, when completed, became the alleged copyright infringer in this suit; it was called the Dentcom PC program ("Dentcom program").19
It appears that Rand Jaslow was sanguine about the prospects of his program for smaller computers. After approximately a year of work, on May 31, 1983, his attorney sent a letter to Whelan Associates giving one month notice of termination of the agreement between Whelan Associates and Jaslow Lab. The letter stated that Jaslow Lab considered itself to be the exclusive marketer of the Dentalab program which, the letter stated, "contains valuable trade secrets of Jaslow Dental Laboratory." The letter concluded with a thinly veiled threat to Whelan Associates: "I ... look for your immediate response confirming that you will respect the rights of Jaslow and not use or disclose to others the trade secrets of Jaslow." App. at 1221.20
Approximately two months later, on about August 1, Edward and Rand Jaslow, Paul Mohr, and Joseph Cerra formed defendant-appellant Dentcom to sell the Dentcom  program. At about the same time, Rand Jaslow and Jaslow Lab employed a professional computer programmer, Jonathan Novak, to complete the Dentcom program. The program was soon finished, and Dentcom proceeded to sell it to dental prosthetics companies that had personal computers. Dentcom sold both the Dentalab and Dentcom programs, and advertised the Dentcom program as "a new version of the Dentalab computer system." App. at 178; 1567-73; 1766-69.21
Despite Jaslow Lab's May 31 letter warning Whelan Associates not to sell the Dentalab program, Whelan Associates continued to market Dentalab. This precipitated the present litigation.22
On June 30, 1983, Jaslow Lab filed suit in the Court of Common Pleas of Montgomery County (Pennsylvania), alleging that Whelan Associates had misappropriated its trade secrets. Whelan Associates responded by filing the instant suit in the United States District Court for the Eastern District of Pennsylvania on September 21, 1983. As set forth in its amended complaint, Whelan Associates alleged that Dentcom's licensing of the Dentalab and Dentcom programs infringed Whelan Associates' copyright in Dentalab, App. at 452-53; that Dentcom's use of the terms "Dentlab" or "Dentalab," violated Pennsylvania common law and 15 U.S.C. § 1125(a) (Lanham Trademark Act of 1946) (false designation of origin), App. at 454-57; and that Dentcom's activities violated various other federal and state laws pertaining to unfair competition and tortious interference with contractual relations, App. at 457-63. Whelan Associates sought injunctive relief, as well as compensatory and punitive damages. App. at 464-69.24
Jaslow Lab and its co-defendants answered, denying all liability. They claimed that Whelan Associates' copyright was invalid for two reasons. First, they said that although he had not been listed in the copyright registration, Rand Jaslow had been a co-author (with Elaine Whelan) of the Dentalab program. The omission of Rand Jaslow from the registration form, defendants averred, rendered the copyright defective. App. at 506-09. Second, the defendants maintained that even if Rand Jaslow had not co-authored the program, he owned the copyright because the program had been written by someone employed by him. App. at 507. Defendants also averred that Rand Jaslow had developed the Dentcom system independently, and therefore could not have violated Whelan Associate's copyright, even if the copyright were valid. Finally, defendants claimed that their use of "Dentalab" or "Dentlab" violated neither federal nor state law, for, inter alia, those terms are merely general descriptions of goods and services, not names of particular products. App. at 504. Defendants counterclaimed that Whelan Associates had usurped defendants' copyright and that by continuing to sell Dentalab, Whelan Associates was engaging in unfair competition. App. at 505-11. By agreement of the parties, the trade secret action was removed from the Court of Common  Pleas to the district court and became a counterclaim. App. at 509-12.25
The first procedural blow was struck by the defendants, who moved almost immediately for a preliminary injunction to enjoin Whelan Associates from using Jaslow Labs' trade secrets. After a three-day hearing, the district court denied the motion in a bench opinion delivered on November 2, 1983. The court held that the defendants had not shown a likelihood of success on the merits because they had failed to prove that any of Jaslow Lab's trade secrets were in the Dentalab program. Moreover, the court held that the defendants' had not proven irreparable harm and that they had approached the court with "unclean hands" on account of their use of the term "Dentlab," which could be and was confused for Dentalab. App. 443-44; 446-47.26
A quick victory proving beyond the defendants' reach, the parties prepared for a protracted battle. Discovery proceeded on each side, and a three-day bench trial began on July 9, 1984. At trial, Whelan Associates continued to press all of its claims — copyright violations, unfair competition, and tortious interference with contractual relations. The defendants abandoned the trade secret claim that had failed them in the preliminary injunction battle, but maintained their position that Rand Jaslow owned the copyright to Dentalab. Defendants continued to deny Whelan Associates' allegations.27
The principal witnesses were Elaine Whelan, Rand Jaslow, and two expert witnesses, Dr. Thomas Moore for Whelan Associates and Stephen Ness on behalf of the defendants. Whelan and Jaslow testified about the dealings and negotiations between the parties. Dr. Moore and Mr. Ness examined the programs and testified about the programs' similarities and differences. Dr. Moore testified that although the Dentcom program was not a translation of the Dentalab system, the programs were similar in three significant respects. He testified that most of the file structures, and the screen outputs, of the programs were virtually identical. App. at 682-704 (file structures); id. at 681-82 (screen outputs). He also testified that five particularly important "subroutines" within both programs — order entry, invoicing, accounts receivable, end of day procedure, and end of month procedure — performed almost identically in both programs. App. at 704-18. Mr. Ness compared the source and object codes of the Dentalab, Dentcom, and Datamaster programs, see supra n. 4, and testified at length about the many ways that the programs differed from one another. He concluded that "substantive differences in programming style, in programming structure, in algorithms and data structures, all indicate that the Dentcom system is not directly derived from either of the other systems." App. at 823-24. In his written report, however, which was entered into evidence, Mr. Ness conceded that the Dentalab and Dentcom programs had "overall structural similarities." App. at 1798.28
The district court ruled for Whelan Associates on all grounds. Whelan Associates v. Jaslow Dental Laboratory, 609 F.Supp. 1307 (E.D.Pa.1985). It found that Elaine Whelan was the sole author of the Dentalab system (and, hence, that Rand Jaslow was not a co-author) and that the contract between Strohl and Rand Jaslow, see supra n. 2, made clear that Strohl would retain full ownership over the software. Whelan Associates v. Jaslow Dental Laboratory, 609 F.Supp. at 1318-19. The court thus concluded that Whelan Associates' copyright in the Dentalab System was valid, and that Dentcom's sales of the Dentalab program were violations of that copyright. Id. at 1320.29
The court also found that Rand Jaslow had not created the Dentcom system independently,  and that the Dentcom system, although written in a different computer language from the Dentalab, and although not a direct transliteration of Dentalab, was substantially similar to Dentalab because its structure and overall organization were substantially similar. Id. at 1321-22. (The district court's opinion on this point is described infra at 1238-39). This substantial similarity, in conjunction with Rand Jaslow's acknowledged access to the Dentalab system, led the district court to conclude that each sale of the Dentcom program by Dentcom violated Whelan Associates' copyright on the Dentalab system. The court therefore awarded Whelan Associates damages for these copyright infringements, and enjoined Dentcom from selling any more copies of the Dentalab or Dentcom programs. Whelan Associates v. Jaslow Dental Laboratory, 609 F.Supp. at 1322-23. The court also held that plaintiffs had exclusive use of the term "Dentalab," and enjoined defendants from using either "Dentalab" or "Dentlab" in their business. Id. at 1324-25.30
The parties filed a series of post-trial motions, primarily concerned with damage calculations and attorneys fees. Upon the district court's disposition of these motions, Whelan Associates v. Jaslow Dental Laboratory, 609 F.Supp. 1325 (E.D.Pa.1985), the defendants filed their notices of appeal. On appeal, they raise a single issue: whether the district court erred in its finding that the Dentcom program infringes the copyright of plaintiffs' Dentalab system.31
We begin with a brief description of computer programs and an explanation of how they are written. This introduction is necessary to our analysis of the issue in this case.33
A computer program is a set of instructions to the computer. Most programs accept and process user-supplied data. The fundamental processes utilized by a program are called algorithms (mechanical computational procedures) and are at the heart of the program. See Keplinger, Computer Software — Its Nature and its Protection, 30 Emory L.J. 483, 484-85 (1984). These algorithms must be developed by the human creativity of the programmer, and the program therefore cannot contain any algorithms not already considered by humans. Although a computer cannot think or develop algorithms, it can execute them faster and more accurately than any human possibly could. See R. Saltman, Copyright in Computer-Readable Works 59 (1977).34
The creation of a program often takes place in several steps, moving from the general to the specific. Because programs are intended to accomplish particular tasks, the first step in creating the program is identifying the problem that the computer programmer is trying to solve. In this case, Rand Jaslow went to Strohl and stated that his problem was record-keeping for his business. Although this was an accurate statement of the problem, it was not specific enough to guide Elaine Whelan. Before she could write the Dentalab program, she needed to know more about Jaslow Lab's business — how orders were processed, what special billing problems might arise, how inventory might be correlated to orders, and other characteristics of the dental prosthetics trade.35
 As the programmer learns more about the problem, she or he may begin to outline a solution. The outline can take the form of a flowchart, which will break down the solution into a series of smaller units called "subroutines" or "modules," each of which deals with elements of the larger problem. See Note, Defining the Scope of Copyright Protection for Computer Software, 38 Stan.L.Rev. 497, 500-01 (1986). A program's efficiency depends in large part on the arrangements of its modules and subroutines; although two programs could produce the same result, one might be more efficient because of different internal arrangements of modules and subroutines. Because efficiency is a prime concern in computer programs (an efficient program being obviously more valuable than a comparatively inefficient one), the arrangement of modules and subroutines is a critical factor for any programmer. In the present case, the Dentalab program had numerous modules pertaining to inventory, accounts receivable, various dentist-patient matters, and payroll, among others. See App. at 1588-1698 (showing flowcharts of subroutines). Some of the modules were simple; others were quite complex and involved elaborate logical development.36
As the program structure is refined, the programmer must make decisions about what data are needed, where along the program's operations the data should be introduced, how the data should be inputted, and how it should be combined with other data. The arrangement of the data is accomplished by means of data files, discussed infra at 1242-44, and is affected by the details of the program's subroutines and modules, for different arrangements of subroutines and modules may require data in different forms. Once again, there are numerous ways the programmer can solve the data-organization problems she or he faces. Each solution may have particular characteristics — efficiencies or inefficiencies, conveniences or quirks — that differentiate it from other solutions and make the overall program more or less desirable. Because the Dentalab program was intended to handle all of the business-related aspects of a dental laboratory, it had to accommodate and interrelate many different pieces and types of data including patients' names, dentists' names, inventory, accounts receivable, accounts payable, and payroll.37
Once the detailed design of the program is completed, the coding begins. Each of the steps identified in the design must be turned into a language that the computer can understand. This translation process in itself requires two steps. The programmer first writes in a "source code," which may be in one of several languages, such as COBOL, BASIC, FORTRAN, or EDL. The choice of language depends upon which computers the programmer intends the program to be used by, for some computers can read only certain languages. Once the program is written in source code, it is translated into "object code," which is a binary code, simply a concatenation of  "0"s and "1"s. In every program, it is the object code, not the source code, that directs the computer to perform functions. The object code is therefore the final instruction to the computer.,38
As this brief summary demonstrates, the coding process is a comparatively small part of programming. By far the larger portion of the expense and difficulty in creating computer programs is attributable to the development of the structure and logic of the program, and to debugging, documentation and maintenance, rather than to the coding. See Frank, Critical Issues in Software 22 (1983) (only 20% of the cost of program development goes into coding); Zelkowitz, Perspective on Software Engineering, 10 Computing Surveys 197-216 (June, 1978). See also InfoWorld, Nov. 11, 1985 at 13 ("the `look and feel' of a computer software product often involves much more creativity and often is of greater commercial value than the program code which implements the product ..."). The evidence in this case shows that Ms. Whelan spent a tremendous amount of time studying Jaslow Labs, organizing the modules and subroutines for the Dentalab program, and working out the data arrangements, and a comparatively small amount of time actually coding the Dentalab program.39
A. The elements of a copyright infringement action — To prove that its copyright has been infringed, Whelan Associates must show two things: that it owned the copyright on Dentalab, and that Rand Jaslow copied Dentalab in making the Dentacom program. Sid & Marty Krofft Television Prods., Inc. v. McDonald's Corp., 562 F.2d 1157, 1162 (9th Cir.1977); Reyher v. Children's Television Workshop, 533 F.2d 87, 90 (2d Cir.), cert. denied, 429 U.S. 980, 97 S.Ct. 492, 50 L.Ed.2d 588 (1976); 3 Nimmer On Copyright § 13.01 (1985) [referred to hereinafter as "Nimmer"]. Although it was disputed below, see supra 1228, the district court determined, and it is not challenged here, that Whelan Associates owned the copyright to the Dentalab program. We are thus concerned only with whether it has been shown that Rand Jaslow copied the Dentalab program.41
As it is rarely possible to prove copying through direct evidence, Roth Greeting Cards v. United Card Co., 429 F.2d 1106, 1110 (9th Cir.1970), copying may  be proved inferentially by showing that the defendant had access to the allegedly infringed copyrighted work and that the allegedly infringing work is substantially similar to the copyrighted work. Ferguson v. National Broadcasting Co., 584 F.2d 111, 113 (5th Cir.1978); Sid & Marty Krofft Television Prods. Inc., supra; Universal Athletic Sales Co. v. Salkeld, 511 F.2d 904, 907 (3d Cir.), cert. denied, 423 U.S. 863, 96 S.Ct. 122, 46 L.Ed.2d 92 (1975); Midway Mfg. Co. v. Strohon, 564 F.Supp. 741, 753 (N.D.Ill.1983). The district court found, and here it is uncontested, that Rand Jaslow had access to the Dentalab program, both because Dentalab was the program used in Jaslow Labs and because Rand Jaslow acted as a sales representative for Whelan Associates. See Whelan Associates v. Jaslow Dental Laboratory, 609 F.Supp. at 1314. Thus, the sole question is whether there was substantial similarity between the Dentcom and Dentalab programs.42
B. The appropriate test for substantial similarity in computer program cases — The leading case of Arnstein v. Porter, 154 F.2d 464, 468-69 (2d Cir.1946), suggested a bifurcated substantial similarity test whereby a finder of fact makes two findings of substantial similarity to support a copyright violation. First, the fact-finder must decide whether there is sufficient similarity between the two works in question to conclude that the alleged infringer used the copyrighted work in making his own. On this issue, expert testimony may be received to aid the trier of fact. (This has been referred to as the "extrinsic" test of substantial similarity. Sid & Marty Krofft Television Prods., Inc. v. McDonald's Corp., 562 F.2d at 1164-65.) Second, if the answer to the first question is in the affirmative, the fact-finder must decide without the aid of expert testimony, but with the perspective of the "lay observer," whether the copying was "illicit," or "an unlawful appropriation" of the copyrighted work. (This has been termed an "intrinsic" test of substantial similarity. Id.) The Arnstein test has been adopted in this circuit. See Universal Athletic Sales Co., 511 F.2d at 907.43
The district court heard expert testimony. See supra 1228; infra at 1246-48. It did not bifurcate its analysis, however, but made only a single finding of substantial similarity. See Whelan Associates v. Jaslow Dental Laboratory, 609 F.Supp. at 1321-22. It would thus appear to have contravened the law of this circuit. Nevertheless, for the reasons that follow, we believe that the district court applied an appropriate standard.44
The ordinary observer test, which was developed in cases involving novels, plays, and paintings, and which does not permit expert testimony, is of doubtful value in cases involving computer programs on account of the programs' complexity and unfamiliarity to most members of the public. See Note, Copyright Infringement of Computer Programs: A Modification of the Substantial Similarity Test, 68 Minn.L.Rev. 1264, 1285-88 (1984). Cf. Note, Copyright Infringement Actions: The Proper Role for Audience Reactions in Determining Substantial Similarity, 54 S.Cal.L.Rev. 385 (1981) (criticizing lay observer standard when objects in question are intended for particular, identifiable audiences). Moreover, the distinction between the two parts of the Arnstein test may be of doubtful value when the finder of fact is the same person for each step: that person has been exposed to expert  evidence in the first step, yet she or he is supposed to ignore or "forget" that evidence in analyzing the problem under the second step. Especially in complex cases, we doubt that the "forgetting" can be effective when the expert testimony is essential to even the most fundamental understanding of the objects in question.45
On account of these problems with the standard, we believe that the ordinary observer test is not useful and is potentially misleading when the subjects of the copyright are particularly complex, such as computer programs. We therefore join the growing number of courts which do not apply the ordinary observer test in copyright cases involving exceptionally difficult materials, like computer programs, but instead adopt a single substantial similarity inquiry according to which both lay and expert testimony would be admissible. See E.F. Johnson Co. v. Uniden Corp., 623 F.Supp. 1485, 1493 (D.Minn.1985); Hubco Data Products Corp. v. Management Assistance Inc., 2 Copyright L.Rep. (CCH) ¶ 25,529 (D.Idaho Feb. 3, 1983) (enunciating bifurcated test, but relying entirely on expert testimony); Midway Mfg. Co. v. Strohon, 564 F.Supp. 741, 752-53 (N.D.Ill.1983) (relying entirely on expert testimony to find substantial similarity); see also Fed.R.Evid. 702 ("If [expert testimony] will assist the trier of fact to understand the evidence or to determine a fact in issue, a witness ... may testify thereto in the form of an opinion or otherwise."). That was the test applied by the district court in this case.46
C. The arguments on appeal — On appeal, the defendants attack on two grounds the district court's holding that there was sufficient evidence of substantial similarity. First, the defendants argue that because the district court did not find any similarity between the "literal" elements (source and object code) of the programs, but only similarity in their overall structures, its finding of substantial similarity was incorrect, for the copyright covers only the literal elements of computer programs, not their overall structures. Defendants' second argument is that even if the protection of copyright law extends to "non-literal" elements such as the structure of computer programs, there was not sufficient evidence of substantial similarity to sustain the district court's holding in this case. We consider these arguments in turn.47
It is well, though recently, established that copyright protection extends to a program's source and object codes. Stern Electronics, Inc. v. Kaufman, 669 F.2d 852, 855 n. 3 (2d Cir.1982) (source code); Apple Computer, Inc. v. Franklin Computer Corp., 714 F.2d 1240, 1246-47 (3d Cir.1983) (source and object code), cert. dismissed, 464 U.S. 1033, 104 S.Ct. 690, 79 L.Ed.2d 158 (1984); Williams Electronics, Inc. v. Artic International, Inc., 685 F.2d 870 (3d Cir.1982) (object code). In this case, however, the district court did not find any copying of the source or object codes, nor did the plaintiff allege such copying. Rather, the district court held that the Dentalab copyright was infringed because the overall structure of Dentcom was substantially similar to the overall structure of Dentalab. Whelan Associates v. Jaslow Dental Laboratory, 609 F.Supp. at 1321-22. The question  therefore arises whether mere similarity in the overall structure of programs can be the basis for a copyright infringement, or, put differently, whether a program's copyright protection covers the structure of the program or only the program's literal elements, i.e., its source and object codes.49
Title 17 U.S.C. § 102(a)(1) extends copyright protection to "literary works," and computer programs are classified as literary works for the purposes of copyright. See H.R.Rep. No. 1476, 94th Cong., 2d Sess. 54, reprinted in 1976 U.S.Code Cong. & Ad.News 5659, 5667. The copyrights of other literary works can be infringed even when there is no substantial similarity between the works' literal elements. One can violate the copyright of a play or book by copying its plot or plot devices. See, e.g., Twentieth Century-Fox Film Corp. v. MCA, Inc., 715 F.2d 1327, 1329 (9th Cir.1983) (13 alleged distinctive plot similarities between Battlestar Galactica and Star Wars may be basis for a finding of copyright violation); Sid & Marty Krofft Television Productions, Inc., 562 F.2d at 1167 (similarities between McDonaldland characters and H.R. Pufnstuf characters can be established by "`total concept and feel'" of the two productions (quoting Roth Greeting Cards v. United Card Co., 429 F.2d 1106, 1110 (9th Cir.1970)); Sheldon v. Metro-Goldwyn Pictures Corp., 81 F.2d 49, 54-55 (2nd Cir.1936); Nichols v. Universal Pictures Corp., 45 F.2d 119, 121 (2d Cir.1930) (copyright "cannot be limited literally to the text, else a plagiarist would escape by immaterial variations"). By analogy to other literary works, it would thus appear that the copyrights of computer programs can be infringed even absent copying of the literal elements of the program. Defendants contend, however, that what is true of other literary works is not true of computer programs. They assert two principal reasons, which we consider in turn.50
A. Section 102(b) and the dichotomy between idea and expression — It is axiomatic that copyright does not protect ideas, but only expressions of ideas. This rule, first enunciated in Baker v. Selden, 101 U.S. (11 Otto) 99, 25 L.Ed. 841 (1879), has been repeated in numerous cases. See, e.g., Mazur v. Stein, 347 U.S. 201, 217, 74 S.Ct. 460, 470, 98 L.Ed. 630 (1954) ("Unlike a patent, a copyright gives no exclusive right to the art disclosed; protection is given only to the expression of the idea — not the idea itself." (citation omitted)); Universal Athletic Sales Co., 511 F.2d at 906; Dymow v. Bolton, 11 F.2d 690, 691 (2d Cir.1926); see generally A. Latman, The Copyright Law 31-35 (5th ed. 1979); 1 Nimmer § 2.03[D]. The rule has also been embodied in statute. Title 17 U.S.C. § 102(b) (1982) states:51
In no case does copyright protection for an original work of authorship extend to any idea, procedure, process, system, method of operation, concept, principle, or discovery, regardless of the form in which it is described, explained, illustrated, or embodied in such work.
The legislative history of this section, adopted in 1976, makes clear that § 102(b) was intended to express the idea-expression dichotomy. See H.R.Rep. No. 1476 at 57, reprinted in 1976 U.S.Code Cong. & Ad.News at 5670 (§ 102(b) is intended to "restate ... that the basic dichotomy between expression and idea remains unchanged.") See also Apple Computer, supra, 714 F.2d at 1252.53
 Defendants argue that the structure of a computer program is, by definition, the idea and not the expression of the idea, and therefore that the structure cannot be protected by the program copyright. Under the defendants' approach, any other decision would be contrary to § 102(b). We divide our consideration of this argument into two parts. First, we examine the case-law concerning the distinction between idea and expression, and derive from it a rule for distinguishing idea from expression in the context of computer programs. We then apply that rule to the facts of this case.54
1. A rule for distinguishing idea from expression in computer programs — It is frequently difficult to distinguish the idea from the expression thereof. No less an authority than Learned Hand, after a career that included writing some of the leading copyright opinions, concluded that the distinction will "inevitably be ad hoc." Peter Pan Fabrics, Inc. v. Martin Weiner Corp., 274 F.2d 487, 489 (2d Cir.1960). See also Knowles & Palmieri, Dissecting Krofft: An Expression of New Ideas in Copyright?, 8 San.Fern.Val.L.Rev. 109, 126 (1980) (arguing that there can be no meaningful distinction between idea and expression). Although we acknowledge the wisdom of Judge Hand's remark, we feel that a review of relevant copyright precedent will enable us to formulate a rule applicable in this case. In addition, precisely because the line between idea and expression is elusive, we must pay particular attention to the pragmatic considerations that underlie the distinction and copyright law generally. In this regard, we must remember that the purpose of the copyright law is to create the most efficient and productive balance between protection (incentive) and dissemination of information, to promote learning, culture and development. See U.S. Const. Art. I, § 8, cl. 8 (Copyright Clause) (giving Congress the power to "promote the Progress of Science ... by securing for limited Times to Authors ... the exclusive Right to their respective Writings".55
We begin our analysis with the case of Baker v. Selden, which, in addition to being a seminal case in the law of copyright generally, is particularly relevant here because, like the instant case, it involved a utilitarian work, rather than an artistic or fictional one. In Baker v. Selden, the plaintiff Selden obtained a copyright on his book, "Selden's Condensed Ledger, or Bookkeeping Simplified," which described a new, simplified system of accounting. Included in the book were certain "blank forms," pages with ruled lines and headings, for use in Selden's accounting system. Selden alleged that Baker had infringed Selden's copyright by making and selling accounting books that used substantially the same system as Selden's and that reproduced Selden's blank forms. No one disputed that Baker had the right to use and promulgate Selden's system of accounting, for all parties agreed that the system could not be copyrighted, although the Court opined that it might be patentable. Id., 101 U.S. at 102. Nor did the parties dispute that the text of Baker's book on accounting did not infringe Selden's copyright. The dispute centered on whether Selden's blank forms were part of the method (idea) of Selden's book, and hence non-copyrightable, or part of the copyrightable text (expression). Id. at 101.56
 In deciding this point, the Court distinguished what was protectible from what was not protectible as follows:57
[W]here the art [i.e., the method of accounting] it teaches cannot be used without employing the methods and diagrams used to illustrate the book, or such as are similar to them, such methods and diagrams are to be considered as necessary incidents to the art, and given to the public.
Id. at 103. Applying this test, the Court held that the blank forms were necessary incidents to Selden's method of accounting, and hence were not entitled to any copyright protection. Id. at 104.59
The Court's test in Baker v. Selden suggests a way to distinguish idea from expression. Just as Baker v. Selden focused on the end sought to be achieved by Selden's book, the line between idea and expression may be drawn with reference to the end sought to be achieved by the work in question. In other words, the purpose or function of a utilitarian work would be the work's idea, and everything that is not necessary to that purpose or function would be part of the expression of the idea. Cf. Apple Computer, Inc. v. Formula Int'l, Inc., 562 F.Supp. 775, 783 (C.D.Ca.1983) ("Apple seeks here not to protect ideas (i.e. making the machine perform particular functions) but rather to protect their particular expressions ..."), aff'd, 725 F.2d 521 (9th Cir.1984). Where there are various means of achieving the desired purpose, then the particular means chosen is not necessary to the purpose; hence, there is expression, not idea.60
Consideration of copyright doctrines related to scenes a faire and fact-intensive works supports our formulation, for they reflect the same underlying principle. Scenes a faire are "incidents, characters or settings which are as a practical matter indispensable ... in the treatment of a given topic." Atari, Inc. v. North American Philips Consumer Elecs. Corp., 672 F.2d 607, 616 (7th Cir.), cert. denied, 459 U.S. 880, 103 S.Ct. 176, 74 L.Ed.2d 145 (1982). See also See v. Durang, 711 F.2d 141, 143 (9th Cir.1983). It is well-settled doctrine that scenes a faire are afforded no copyright protection.61
Scenes a faire are afforded no protection because the subject matter represented can be expressed in no other way than through the particular scene a faire. Therefore, granting a copyright "would give the first author a monopoly on the commonplace ideas behind the scenes a faire." Landsberg v. Scrabble Crossword Game Players, Inc., 736 F.2d at 489. This is merely a restatement of the hypothesis advanced above, that the purpose or function of a work or literary device is part of that device's "idea" (unprotectible portion). It follows that anything necessary to effecting that function is also, necessarily, part of the idea, too.62
Fact intensive works are given similarly limited copyright coverage. See, e.g., Landsberg, 736 F.2d at 488; Miller v. Universal  City Studios, Inc., 650 F.2d 1365, 1372 (5th Cir.1981). Once again, the reason appears to be that there are only a limited number of ways to express factual material, and therefore the purpose of the literary work — telling a truthful story — can be accomplished only by employing one of a limited number of devices. Landsberg, 736 F.2d at 488. Those devices therefore belong to the idea, not the expression, of the historical or factual work.63
Although the economic implications of this rule are necessarily somewhat speculative, we nevertheless believe that the rule would advance the basic purpose underlying the idea/expression distinction, "the preservation of the balance between competition and protection reflected in the patent and copyright laws." Herbert Rosenthal Jewelry Corp. v. Kalpakian, 446 F.2d 738, 742 (9th Cir.1971); see also Apple Computer, 714 F.2d at 1253 (quoting Kalpakian); supra n. 27. As we stated above, see supra at 1231, among the more significant costs in computer programming are those attributable to developing the structure and logic of the program. The rule proposed here, which allows copyright protection beyond the literal computer code, would provide the proper incentive for programmers by protecting their most valuable efforts, while not giving them a stranglehold over the development of new computer devices that accomplish the same end.64
The principal economic argument used against this position — used, that is, in support of the position that programs' literal elements are the only parts of the programs protected by the copyright law — is that computer programs are so intricate, each step so dependent on all of the other steps, that they are almost impossible to copy except literally, and that anyone who attempts to copy the structure of a program without copying its literal elements must expend a tremendous amount of effort and creativity. In the words of one commentator: "One cannot simply `approximate' the entire copyrighted computer program and create a similar operative program without the expenditure of almost the same amount of time as the original programmer expended." Note, 68 Minn.L.Rev. at 1290 (footnote omitted). According to this argument, such work should not be discouraged or penalized. A further argument against our position is not economic but jurisprudential; another commentator argues that the concept of structure in computer programs is too vague to be useful in copyright cases. Radcliffe, Recent Developments in Copyright Law Related to Computer Software, 4 Computer L.Rep. 189, 194-97 (1985). He too would therefore appear to advocate limiting copyright protection to programs' literal codes.65
Neither of the two arguments just described is persuasive. The first argument fails for two reasons. In the first place, it is simply not true that "approximation" of a program short of perfect reproduction is valueless. To the contrary, one can approximate a program and thereby gain a significant advantage over competitors even though additional work is needed to complete the program. Second, the fact that it will take a great deal of effort to copy a copyrighted work does not mean that the copier is not a copyright infringer. The issue in a copyrighted case is simply whether the copyright holder's expression has been copied, not how difficult it was to do the copying. Whether an alleged infringer spent significant time and effort to copy an original work is therefore irrelevant to whether he has pirated the expression of an original work.66
As to the second argument, it is surely true that limiting copyright protection to  computers' literal codes would be simpler and would yield more definite answers than does our answer here. Ease of application is not, however, a sufficient counterweight to the considerations we have adduced on behalf of our position.67
Finally, one commentator argues that the process of development and progress in the field of computer programming is significantly different from that in other fields, and therefore requires a particularly restricted application of the copyright law. According to this argument, progress in the area of computer technology is achieved by means of "stepping-stones," a process that "requires plagiarizing in some manner the underlying copyrighted work." Note, 68 Minn.L.Rev. at 1292 (footnote omitted). As a consequence, this commentator argues, giving computer programs too much copyright protection will retard progress in the field.68
We are not convinced that progress in computer technology or technique is qualitatively different from progress in other areas of science or the arts. In balancing protection and dissemination, see supra at 1235 & n. 27, the copyright law has always recognized and tried to accommodate the fact that all intellectual pioneers build on the work of their predecessors. Thus, copyright principles derived from other areas are applicable in the field of computer programs.69
2. Application of the general rule to this case — The rule proposed here is certainly not problem-free. The rule has its greatest force in the analysis of utilitarian or "functional" works, for the purpose of such works is easily stated and identified. By contrast, in cases involving works of literature or "non-functional" visual representations, defining the purpose of the work may be difficult. Since it may be impossible to discuss the purpose or function of a novel, poem, sculpture or painting, the rule may have little or no application to cases involving such works. The present case presents no such difficulties, for it is clear that the purpose of the utilitarian Dentalab program was to aid in the business operations of a dental laboratory. See supra 1225. It is equally clear that the structure of the program was not essential to that task: there are other programs on the market, competitors of Dentalab and Dentcom, that perform the same functions but have different structures and designs.70
This fact seems to have been dispositive for the district court:71
The mere idea or concept of a computerized program for operating a dental laboratory would not in and of itself be subject to copyright. Copyright law protects the manner in which the author expresses an idea or concept, but not the idea itself. Albert E. Price v. Metzner, 574 F.Supp. 281 (E.D.Pa.1983). Copyrights do not protect ideas — only expressions of ideas. Universal Athletic Sales Co. v. Salkeld, 511 F.2d 904, 908 (3d Cir.1975). There are many ways that the same data may be organized, assembled, held, retrieved and utilized by a computer. Different computer systems may functionally serve similar purposes without being copies of each other. There is evidence in the record that there are other software programs for the business management of dental laboratories in competition with plaintiff's program. There is no contention that any of them infringe although  they may incorporate many of the same ideas and functions. The `expression of the idea' in a software computer program is the manner in which the program operates, controls and regulates the computer in receiving, assembling, calculating, retaining, correlating, and producing useful information either on a screen, print-out or by audio communication.
Whelan Associates v. Jaslow Laboratory, 609 F.Supp. at 1320 (emphasis added). We agree. The conclusion is thus inescapable that the detailed structure of the Dentalab program is part of the expression, not the idea, of that program.73
Our conclusion is supported by SAS Institute, Inc. v. S & H Computer Systems, Inc., 605 F.Supp. 816 (M.D.Tenn.1985), the only other case that has addressed this issue specifically, in which the court found that a program's copyright could extend beyond its literal elements to its structure and organization. In SAS, plaintiffs supported their allegation of copyright infringement of their computer program with evidence of both literal and organizational similarities between its program and the alleged infringer. Id. at 822, 825-26. The court found a copyright infringement, and although it did not discuss in detail its evaluation of the evidence, it is apparent that the organizational similarities of the programs were relevant to its decision. After a brief discussion of the programs' literal similarities, the court said:74
In addition, the copying proven at trial does not affect only the specific lines of code cited by Dr. Peterson in his testimony. Rather, to the extent that it represents copying of the organization and structural details of SAS, such copying pervades the entire S & H product.
Id. at 830. Although the SAS court did not analyze the point in great depth, we are encouraged by its conclusion.76
The Copyright Act of 1976 provides further support, for it indicates that Congress intended that the structure and organization of a literary work could be part of its expression protectible by copyright. Title 17 U.S.C. § 103 (1982) specifically extends copyright protection to compilations and derivative works. Title 17 U.S.C. § 101, defines "compilation" as "a work formed by the collection and assembling of preexisting materials or of data that are selected, coordinated, or arranged in such a way that the resulting work as a whole constitutes an original work of authorship," and it defines "derivative work," as one "based upon one or more preexisting works, such as ... abridgement, condensation, or any other form in which a work may be recast, transformed, or adapted." (emphasis added). Although the Code does not use the terms "sequence," "order" or "structure," it is clear from the definition of compilations and derivative works, and the protection afforded them, that Congress was aware of the fact that the sequencing and ordering of materials could be copyrighted, i.e., that the sequence and order could be parts of the expression, not the idea, of a work.77
Our solution may put us at odds with Judge Patrick Higginbotham's scholarly opinion in Synercom Technology, Inc. v. University Computing Co., 462 F.Supp. 1003 (N.D.Tex.1978), which dealt with the question whether the "input formats" of a computer program — the configurations and collations of the information entered into the program — were idea or expression. The court held that the input formats were ideas, not expressions, and thus not protectible. Synercom did not deal with precisely the materials at issue here — input formats are structurally simple as compared to full programs — and it may therefore be distinguishable. However, insofar as the input formats are devices for the organization of data into forms useful for computers, they are similar to programs; thus, Synercom is relevant and we must come to grips with it.78
Central to Judge Higginbotham's analysis was his conviction that the organization and structure of the input formats was inseparable from the idea underlying the formats. Although the court acknowledged that in some cases structure and  sequence might be part of expression, not idea, see id. at 1014, it stated that in the case of input formats, structure and organization were inherently part of the idea. The court put its position in the form of a powerful rhetorical question: "if sequencing and ordering [are] expression, what separable idea is being expressed?" Id. at 1013.79
To the extent that Synercom rested on the premise that there was a difference between the copyrightability of sequence and form in the computer context and in any other context, we think that it is incorrect. As just noted, the Copyright Act of 1976 demonstrates that Congress intended sequencing and ordering to be protectible in the appropriate circumstances, see supra p. 1237-1238, and the computer field is not an exception to this general rule. Although Congress was aware that computer programs posed a novel set of issues and problems for the copyright law, Congress did not then make, and has not since made, any special provision for ordering and sequencing in the context of computer programs. There is thus no statutory basis for treating computer programs differently from other literary works in this regard.80
Despite the fact that copyright protection extends to sequence and form in the computer context, unless we are able to answer Judge Higginbotham's powerful rhetorical question — "if sequencing and ordering [are] expression, what separable idea is being expressed?" — in our own case, we would have to hold that the structure of the Dentalab program is part of its idea and is thus not protectible by copyright. Our answer has already been given, however: the idea is the efficient organization of a dental laboratory (presumably, this poses different problems from the efficient organization of some other kinds of laboratories or businesses). Because there are a variety of program structures through which that idea can be expressed, the structure is not a necessary incident to that idea. See supra 1239.81
B. The CONTU Report — Defendants' second argument against copyright protection for non-literal elements of computer programs relies not on venerable principles of copyright law, but on the report of a special congressional commission. In 1974, concerned that the rapidly developing field of computer technology was out-pacing the extant copyright laws, Congress passed Pub.L. 93-573, § 201, 88 Stat.1873 (1974) creating the National Commission on New Technological Uses of Copyrighted Works (CONTU) to study and report on the problems and issues of new technology and copyright.82
In 1976, before CONTU reported its findings to Congress, Congress passed a new copyright law to replace the one that had prevailed since 1909. Pub.L. No. 94-553, 90 Stat. 2541 (1976) (codified at 17 U.S.C.  § 101 et seq.). The new law's only explicit accommodation to computer technology was 17 U.S.C. § 117, which dealt with copyright issues arising upon certain uses of computer programs not in issue here.83
The Commission's Final Report [hereinafter "CONTU Report"] was delivered to the President on July 31, 1978. The CONTU Report recommended legislation:84
The new copyright law should be amended: (1) to make it explicit that computer programs, to the extent that they embody an author's original creation, are proper subject matter for copyright; (2) to apply to all computer uses of copyrighted programs by the deletion of the present section 117; and (3) to ensure that rightful possessors of copies of computer programs may use or adapt these copies for their use.
CONTU Report at 1. Congress responded to these suggestions in the 1980 Computer Software Copyright Act by adding a provision to 17 U.S.C. § 101 defining computer programs, see Pub.L. No. 96-517, § 10(a), 94 Stat. 3028 (1980) (codified at 17 U.S.C. § 101) (quoted supra n. 13). It also replaced the old § 117 with a new § 117 outlining users' rights of adaptation.86
As neither the definition of "computer program" nor 17 U.S.C. § 117 is relevant here, it would appear that the CONTU Report is of marginal relevance, at best. Nevertheless, defendants argue that it is not only relevant, but that it compels a decision in their favor. Specifically, defendants argue that the CONTU Report recommends that copyright protection be limited to protection of the literal elements of computer programs, and that the CONTU Report is to be taken as authoritative legislative history, which this court is bound to follow. Appellants' Br. at 15-21. This argument is unpersuasive, however.87
In the first place, the CONTU Report never suggests that copyright protection should be limited to the literal code. To the contrary, in discussing the limits of copyright protection, the Report referred to the dichotomy between idea and expression discussed above, and said:88
[T]he separation of idea from form of expression ... is better realized through the courts exercising their judgment in particular cases [than by a per se rule].... Flow charts, source codes, and object codes are works of authorship in which copyright subsists....
CONTU Report at 21 (emphasis added). While the first part of this passage suggests that the Commission may have reserved judgment as to the copyrightability of non-literal elements of computer programs, the second part — particularly the reference to the copyrightability of flowcharts — demonstrates that the Commission intended copyright protection to extend beyond the literal code. Thus, the CONTU Report does not support defendants' position in this case.90
Even if the CONTU Report had advocated a strict limitation of the copyrightability of computer programs, defendants' argument would still fail, for the CONTU Report is not binding on us in this case. Defendants correctly note that some courts have treated the CONTU Report as a surrogate legislative history. See, e.g., Micro-Sparc, Inc. v. Amtype Corp., 592 F.Supp. 33, 35 n.7 (D.Mass.1984) ("The CONTU Report ... comprises the entire legislative history of § 117."); Midway Mfg. Co. v. Strohon, 564 F.Supp. 741, 750 n. 6. The courts have said this because Congress adopted the CONTU Report's recommendations without alterations and without any committee reports. Defendants argue that this court, too, is bound by the CONTU Report for the same reason.91
The argument fails, however, for the only statutory provision relevant to this case is § 102(b), see supra 1234-35, in which no changes were made as a result of the CONTU Report. Therefore, it follows  that the CONTU Report cannot be a substitute for legislative history in this case. In effect, defendants ask us to apply the precepts of the CONTU Report regardless of what legislative provision we are considering. We cannot do this, however, for the CONTU Report has force only insofar as it can be said to represent the will of Congress. There is no sense in which it represents the will of Congress with respect to provisions not amended in response to the Report.92
Defendants' second argument is that even if copyright protection is not limited to computer programs' literal elements as a matter of law, there is insufficient evidence of substantial similarity presented in this case to support a finding of copyright infringement. The defendants claim that all three parts of Dr. Moore's expert testimony as to the similarity of the programs, see supra at 1228, were flawed, and also that the district court erred in evaluating the relative weight of Dr. Moore's and Mr. Ness' testimony. We consider these arguments in turn.94
A. File structures — Defendants claim that Dr. Moore's examination and conclusions with respect to file structures are irrelevant to the question whether there was a copyright violation. Defendants analogize files to blank forms, which contain no information but merely collect and organize information that is entered from another source. They argue, relying on Baker v. Selden, that, as a matter of law, blank forms cannot be copyrighted. Thus, they conclude, neither can file structures be part of the copyright of a program. See Appellants' Br. at 34-38; Reply Br. at 7-8.95
Defendants' description of the file structures is indeed correct. Dr. Moore himself described a computer's file as "a storage place for data, and it's really no different in a computer than it is in a file drawer, it's like a manila folder that contains all the data on a particular subject category in a computer." App. at 682. (Another analogy, particularly accessible to lawyers, is to a very complex cataloguing structure like the structure of Lexis or Westlaw without any entries yet made.) Defendants' legal conclusion is not correct, however. Although some courts have stated that the meaning of Baker v. Selden is that blank  forms cannot be copyrighted, this circuit, like the majority of courts that have considered the issue, has rejected this position and instead have held that blank forms may be copyrighted if they are sufficiently innovative that their arrangement of information is itself informative. Apple Computer, Inc., 714 F.2d at 1250. See also Manpower, Inc. v. Temporary Help of Harrisburg, Inc., 246 F.Supp. 788 (E.D.Pa.1965) (upholding copyrightability of form for vacation schedules).96
This is not to say that all blank forms or computer files are copyrightable. Only those that by their arrangement and organization convey some information can be copyrighted. Cf. 1 Nimmer at 2-201: "Thus books intended to record the events of baby's first year, or a record of a European trip, or any one of a number of other subjects, may evince considerable originality in suggestions of specific items of information which are to be recorded, and in the arrangement of such items." (footnote omitted). Defendants do not contend, however, that the file structures convey no information, and it appears to us that the structures are sufficiently complex and detailed that such an argument would not succeed. As we have noted, supra at 1239, there are many ways in which the same goal — the organization of the business aspects of a dental laboratory — might be accomplished, and several of these approaches might use significantly different file structures. The file structures in the Dentalab and Dentcom systems require certain information and order that information in a particular fashion. Other programs might require different information or might use the same information differently. When we compare the comprehensiveness and complexity of the file structures at issue here with the "blank forms" at issue in the cases mentioned above, we have no doubt that these file structures are sufficiently informative to deserve copyright protection.97
B. Screen outputs — Defendants' second line of argument is slightly confusing.  Defendants appear to argue that to the extent that the district court relied upon the similarity of the screen outputs of Dentalab and Dentcom its finding of substantial similarity was erroneous because (1) the screen outputs are covered by a different copyright from the program's, and/or (2) the screen outputs bear no relation to the programs that produce them. Although these arguments are not always clearly distinguished, Appellants' Br. at 38-41; Reply Br. at 8-10, the distinction is important because whereas the first argument is weak, we feel that the second is more persuasive.98
It is true that screen outputs are considered audio-visual works under the copyright code, see Williams Electronics, 685 F.2d at 874; Midway Manufacturing Co., 564 F.Supp. at 749 (distinguishing audiovisual copyright in display of videogame from copyright in program that creates the audiovisual display), and are thus covered by a different copyright than are programs, which are literary works, see supra at 1233. It is also true that Whelan Associates asserts no claim of copyright infringement with respect to the screen outputs. But the conclusion to be drawn from this is not, as defendants would have it, that screen outputs are completely irrelevant to the question whether the copyright in the program has been infringed. Rather, the only conclusion to be drawn from the fact of the different copyrights is that the screen output cannot be direct evidence of copyright infringement. There is no reason, however, why material falling under one copyright category could not be indirect, inferential evidence of the nature of material covered by another copyright.99
Thus, the question is whether the screen outputs have probative value concerning the nature of the programs that render them sufficient to clear the hurdles of Fed.R.Evid. 401 and 403. The defendants argue that the screen outputs have no probative value with respect to the programs because many different programs can create the same screen output. Defendants rely on Stern Electronics Inc. v. Kaufman, 669 F.2d at 855 ("many different computer programs can produce the same `results,' whether those results are an analysis of financial records or a sequence of images and sounds."), and Midway Manufacturing Co., 564 F.Supp. at 749 ("it is quite possible to design a game that would infringe Midway's audiovisual copyright but would use an entirely different computer program."). Neither court, however, was presented with the question that faces us today, the evidentiary value of screen outputs in a suit for infringement of the underlying program.100
Insofar as everything that a computer does, including its screen outputs, is related to the program that operates it, there is necessarily a causal relationship between the program and the screen outputs. The screen outputs must bear some relation to the underlying programs, and therefore they have some probative value. The evidence about the screen outputs therefore passes the low admissibility threshold of Fed.R.Evid. 401.101
 It is still possible, of course, that the risk of unfair prejudice would outweigh the probative value of the evidence, thus contravening Fed.R.Evid. 403. In support of this position one might argue that, because the screen outputs are vivid and easily understood (at least as compared with the obscure details of computer programs), they might have disproportionate influence on the trier of fact. However, because the portions of programs that relate to the screen outputs are often so small a part of the full program, they might say very little about the underlying program. This combination of ease of perception and slight probative value, the argument concludes, works a Rule 403 violation because the screen outputs appear significantly more probative than they in fact can be.102
This argument has force, but we feel that it is ultimately unpersuasive. In the first place, the defendants point to no place in the record where they objected to testimony about the screens' similarities. Our independent review of the record has revealed no such objections. See, e.g., App. at 681-82 (Dr. Moore testifying about screen similarities without objection from defendants). Therefore, because this could not be plain error, the objection was waived. Second, even if the objection had not been waived, we do not believe that admission of the evidence relating to screen similarity suffices for a Rule 403 exclusion. Screen outputs are not so enticing that a trier of fact could not evaluate them rationally and with a cool head. The party against whom the screen outputs are introduced can easily explain their limited probative value. Given the substantial deference with which we review the district court's decision on this matter, see McQueeney v. Wilmington Trust Co., 779 F.2d 916, 922 (3d Cir.1985), and the parties' ample opportunities to advance their arguments before the district court, we do not believe that the district court committed error in considering the evidence relating to screen outputs.103
C. The five subroutines — With respect to the final piece of evidence, Dr. Moore's testimony about the five subroutines found in Dentalab and Dentcom, defendants state that they "fail to understand how a substantial similarity in structure can be established by a comparison of only a small fraction of the two works." Appellants' Brief at 43, see also Reply Br. at 12. The premise underlying this declaration is that one cannot prove substantial similarity of two works without comparing the entirety, or at least the greater part, of the works. We take this premise to be the defendants' argument.104
The premise does not apply in other areas of copyright infringement. There is no general requirement that most of each of two works be compared before a court can conclude that they are substantially similar. In the cases of literary works — novels, movies, or plays, for example — it is often impossible to speak of "most" of the work. The substantial similarity inquiry cannot be simply quantified in such instances. Instead, the court must make a qualitative, not quantitative, judgment about the character of the work as a whole and the importance of the substantially similar portions of the work. See, e.g., Harper & Row Publishers, Inc. v. Nation Enterprises, 471 U.S. 539, ___-___ & ___ n. 8, 105 S.Ct. 2218, 2233-34 & 2233 n. 8, 85 L.Ed.2d 588 (1985); Atari, Inc. v. North American Phillips Consumer Electronics Corp., 672 F.2d 607, 618 (7th Cir.) ("When analyzing two works to determine whether they are substantially similar, courts should be careful not to lose sight of the forest for the trees."), cert. denied, 459 U.S. 880, 103 S.Ct. 176, 74 L.Ed.2d 145 (1982); Hoehling v. Universal City Studios, Inc., 618 F.2d 972, 979-80 (2d Cir.) (warning against same danger), cert. denied, 449 U.S. 841, 101 S.Ct. 121, 66 L.Ed.2d 49 (1980). See also Universal Pictures v. Harold Lloyd Corp., 162 F.2d 354 (9th Cir.1947) (finding copyright violation for copying of 20% of plaintiff's film); In re Personal Computers and Components  Thereof, 1983-84 Copyright L.Dec. (CCH) ¶ 25,651 at 18,931 (Int'l Trade Comm'n Mar. 9, 1984) (18%-25% identity is sufficient for substantial similarity). Compare Elsmere Music, Inc. v. National Broadcasting Co., 482 F.Supp. 741, 744 (S.D.N.Y.), aff'd, 623 F.2d 252 (2d Cir.1980) (similarity uncontested by defendants where four notes out of 100 measures and two words out of 45 were identical) with Jewel Music Publishing Co. v. Leo Feist, Inc., 62 F.Supp. 596, 597 (S.D.N.Y.1945) (finding no substantial similarity where three bars of an eight-bar line were identical and the line appeared 24 times in both songs).105
Computer programs are no different. Because all steps of a computer program are not of equal importance, the relevant inquiry cannot therefore be the purely mechanical one of whether most of the programs' steps are similar. Rather, because we are concerned with the overall similarities between the programs, we must ask whether the most significant steps of the programs are similar. See Midway Mfg. Co. v. Strohon, supra, 564 F.Supp. at 753. This is precisely what Dr. Moore did. He testified as follows:106
What I decided to do was to look at the programs that had the primary, or let's say most important, tasks of the system, and also ones which manipulate files, because there are a lot of programs that simply print lists, or answer a question when you ask him it, but I thought that the programs which actually showed the flow of information, through the system, would be the ones that would illustrate the system back.
App. at 704. Dr. Moore's testimony was thus in accord with general principles of copyright law. As we hold today that these principles apply as well to computer programs, we therefore reject the defendants' argument on this point.108
D. Sufficiency of the evidence — Defendants' final argument is that the district court erred in evaluating the testimony of Dr. Moore and Mr. Ness. They contend that, properly evaluated, Mr. Ness' testimony was sufficiently strong and Dr. Moore's sufficiently weak, that there was not sufficient evidence of substantial similarity for plaintiff to prevail.109
We have described the testimony of Dr. Moore and Mr. Ness, see supra 1227; see also infra 1247-48, and it is recounted in the district court opinion, Whelan Associates v. Jaslow Dental Laboratory, 609 F.Supp. at 1316. The district court explained its evaluation of the evidence as follows:110
I conclude ... that Dr. Moore, plaintiffs' expert, had greater knowledge as to the particular programs at issue. Dr. Hess [sic], the defendants' expert witness, reviewed only the source and object codes of the IBM-Series 1 [Dentalab program], the IBM Datamaster [see supra n. 4], and the IBM-PC Dentcom system. He never observed the computer in operation nor viewed the various screens or the user's manual. He stated he was not familiar with EDL coding. More basically, however, his comparison as to dissimilarities was between the IBM Datamaster and the IBM-PC Dentcom systems. Plaintiff contends that the IBM-PC Dentcom is a copy of the IBM Series 1 System — not the IBM-Datamaster system. Dr. Hess's conclusions were that although the overall structures of those systems is similar, the code in the IBM-PC Dentcom is not "directly derived" from either plaintiff's IBM Series-1 or its IBM-Datamaster system. To the extent that Dr. Moore's testimony supports plaintiff's contentions of copying, I find his testimony more credible and helpful because of his detailed and thorough analysis of the many similarities.
Id. at 1321-22. Determinations of credibility and the relative weight to be given expert witnesses are, of course, left primarily to the discretion of the district court. Our review of the record convinces us that the district court's analysis of the two experts' opinions was far from being erroneous. As the district court pointed out, Mr. Ness had studied the programs, but he had never observed them at work in computers. Id. at 1321. The district court also pointed out  that Mr. Ness was unfamiliar with EDL coding. Id. These factors suffice to support the court's conclusion.112
In addition, we believe, on re-reading the trial transcript, that although Mr. Ness' testimony was quite competent, Dr. Moore's was more persuasive on the issues relevant to this appeal. Whereas the greater part of Mr. Ness' testimony was concerned with the dissimilarities between the two programs' source and object codes, see, e.g., App. at 824-32, Dr. Moore discussed the crucial issue in this case, the similarities and differences in the programs' structures. For example, when he discussed the programs' invoicing subroutine, Dr. Moore testified as follows:113
In the DentaLab system, the same kind of thing again, same information is up there, description, unit price, extension, items and program reads all those things in from te [sic] number of files actually, and displays them and then gives the operator a number of options to change the order as it appears on the screen to skip this one, to cancel it, or to accept it.
The same choices are given in Dentalab systems, change, skip, cancel.
Assuming that the order is accepted, both systems then calculate the money, calculate the amount of money that will be billed, and at this point they use the price code to find which of the four prices are to be charged for this particular customer. Both systems do that. They pick that one of the four prices and calculate the total amount, write [sic] then the record of this invoice that has been formed to show the invoice's file, sets the flag in the order's file to show that this order has now been invoiced so that it doesn't get reinvoiced.
Q. What is a flag?
A. Well, a flag would be, in this case, a certain location is marked I for invoices, just an indicator that invoicing has been done on this record.
Q. Both used it?
A. Both used a flag. I don't remember whether Dentcom uses a letter I or some other symbol, but there is a flag there that it's a field number 12, in which it's indicated that this file has been invoiced or this order has been invoiced.
* * * * * *
Q. Do you have any comment about the invoicing?
A. Well, I think it should be clear, it was clear to me from going through these programs that there is a very marke[d] similarity between the two, that they, item by item, are doing pretty much the same thing with the same fields in the same files, and accomplishing roughly the same results.
So there was quite a match, line by line, between these two, flow in these two.
Q. What do you conclude from that?
A. Well, back together with the file's structure, sort of set up with the — how the programs have to proceed. I would think that the person who designed or constructed the DentaLab system must have been thoroughly familiar with the Dentcom system.
The person who constructed the Dentcom system must have been familiar with the series one system, because the same file structure and same program steps are followed, same overall flow takes place in both systems.
App. at 710-12 (emphasis added). Dr. Moore's testimony about Dentcom's and Dentalab's month-end subroutines also demonstrates the structural comparisons in which he engaged:115
Q. What did you find in month-end?
A. Okay. Month-end, the calling program in Dentcom, this obviously is done at the end of each month.
In the Dentcom system there is a program called MOEND, which chains all these other programs, that is, MOEND calls MOPRDL, and after that program runs, goes back to MEEND, calls the print sale and so on.
In the Dentalab system there is a supervisory program also called MOEND,  and that system calls or runs a series of programs doing various functions.
Now if we look at the functions done by the programs in order, we find that they are the same except for a flipping of the order in the first two things.
The Dentcom system, it first prints product group report, and then prints the monthly customer sales analysis.
In Dentalab, just reverses, prints sales analysis first, product group report second.
After that, both systems do the same thing in the same order.
They now do accounts receivable aging, since a month has gone by they have to update all the 30 days, 60 days, et cetera, calculate service charges. Then they print the monthly AR reports that had to do with service charges, only those that involve service charges, they both do that. Then they both print the age file balance, balance report, and following that they print the month and accounts receivable report. That's the total accounts receivable rport [sic].
Then they both go through and look for accounts that are not active that month, and print a list of these accounts, accounts not serviced, an account that doesn't have any access.
The final thing that the Dentcom system does is to calculate the new AR total for the entire lab, which I mentioned is contained in the company file.
DentaLab doesn't keep that total, so that's the last item, that is not as far as I can tell, done by DentaLab. I may have said — did I say Dentcom keeps that total? DentaLab does not. That's the only difference.
App. at 716-18 (emphasis added). Dr. Moore testified in similar detail and to similar effect about the other three subroutines that he felt were particularly important, order entry, accounts receivable, and day's end. This testimony, in addition to Dr. Moore's exhaustive comparison of the two programs' file structures, see supra 1227, and his testimony about the screen outputs, id., demonstrates the marked similarity between the programs. Defendants' argument as to sufficiency of the evidence therefore fails.117
We hold that (1) copyright protection of computer programs may extend beyond the programs' literal code to their structure, sequence, and organization, and (2) the district court's finding of substantial similarity between the Dentalab and Dentcom programs was not clearly erroneous. The judgment of the district court will therefore be affirmed.119
 APPENDIX A ORDER ENTRY PROGRAMSDentcom PC Systems Dentalab SystemPrimary Menu, choose  Primary Menu, choose Production MENU Production SCHEDULINGProduction menu choose  Production Menu, choose ORDER ENTRY ORDER ENTRYORDER ENTRY program DL1000 program (Order entry)"ENTER ACCOUNT NAME KEY: "ENTER ACCOUNT OR NAMEKEY"-------------------------------------- "Check CUSTMAST for valid customer.Check CUSTMAST for valid customer. If Read CUSTMAST file on this customer.valid, read CUSTMAST file for this customer.If yes, increment order # in ORDERS Increment sequential order no. in ORDERS. Display customer name, address.Display entry screen, patient shade, mould, Display entry screen (6.6), patient shade,remake, call Dr.? remake, callDr.?case/span #, Drs. request date, final case Pan #, Dr's. request date.statut T, F, B, R.IS THIS SCREEN CORRECT?If yes ask for first department number. Ask for first department number. DisplayDisplay dept. order screen (P10) (list of dept. order screen (6.8-6.11) (list of itemsitem in this dept. from ITEMMAST) in this dept. from ITEMMAST)User entry choices User entry choicesSystem adds days in dept. from COMPANY System adds days in dept. [DAYVAL] toto present date to find due out date. Time present date to find due out date. Systemis of AM. "Noon" or PM. System accumulates computes workload for dept/day out bycase load by product of item product of load factor × quantity.load factor × quantity.ITEMMAST ITEMMASTAdds this to load already in DEPTLOAD Add this to load already in DAYVAL forfor date out. date out.120
 We use the terms "structure," "sequence," and "organization" interchangeably when referring to computer programs, and we intend them to be synonymous in this opinion.121
 A letter of August 31, 1978, explained what the program would do for Jaslow Lab and how much it would cost. See App. at 1770-75. A letter from Strohl to Jaslow Lab dated September 20, 1978, supplemented the August 31 proposal as follows:122
This communication is a supplement to our proposal letter dated 8/31/78.
We [Strohl] propose that all software developed by us for your dental laboratory system remain under our ownership. This basic system can then be marketed to similar laboratories by our organization. A royalty of ten percent of the basic package price would be returned to Jaslow Dental Laboratory for each system sold.
Whelan Associates v. Jaslow Dental Laboratory, 609 F.Supp. 1307, 1310 (E.D.Pa.1985) (the district court inadvertently identified the letter as dated September 30, 1978). Although no representative of Jaslow Lab ever signed either agreement, the district court found that Jaslow Lab had, through its conduct, accepted the terms of the letter. Id. at 1310.124
 Rand Jaslow on behalf of Jaslow Lab sent a letter to Whelan Associates on June 22, 1982, stating its intention to terminate business relations in 30 days. However, the parties continued to do business under the agreement of July 30, 1980 until the termination letter of May 31, 1983, discussed below.125
 The record indicates that Whelan Associates also developed a BASIC version of the Dentalab, written specially for the IBM-Datamaster 26 computer. That program [the "Datamaster" program], did not succeed commercially. Whelan Associates has also written a second program in BASIC for dental laboratories' business operations. The second program was intended for use on IBM-PC's. Neither the Datamaster program nor Whelan Associates' program for the IBM-PC is directly at issue here. But see infra 1228 (use of Datamaster program by defendants' expert witness at trial).126
 The district court inadvertently referred to this as the letter of January 31, 1983. See Whelan Associates v. Jaslow Dental Laboratory, 609 F.Supp. 1307, 1313 (E.D.Pa.1985).127
 Joseph Cerra had, from January until June, 1983, been in the employ of Whelan Associates in charge of marketing. In this position, he had had close contact with Rand Jaslow. When he left Whelan Associates, he made a verbal promise to Elaine Whelan that he would not become associated in any business ventures with Rand Jaslow. There was, however, no written agreement. App. at 1088. Although Mr. Cerra was originally named as a defendant, he settled prior to trial.128
The record contains no information about Paul Mohr's employment history or of his previous associations with Whelan Associates or any of the defendants.129
 17 U.S.C. § 106 (1982), which prescribes copyright holders' exclusive rights, forbids the copying of copyrighted works. The independent creation of even identical works is therefore not a copyright infringement, and independent creation is a complete defense to a claim of copyright infringement. See also Fred Fisher, Inc. v. Dillingham, 298 F. 145, 147 (S.D.N.Y.1924) (L. Hand, J.) ("the law imposes no prohibition upon those who, without copying, independently arrive at the precise combination of words or notes which have been copyrighted.").130
 Dr. Moore's testimony is discussed in greater detail infra at 1246-48.131
 Source and object code are defined infra at 1230-31.132
 There were two such sales by Dentcom.133
 There were 23 such sales.134
 The appeal is from the court's injunction preventing defendants from selling the Dentcom program. The court has not yet entered a final judgment covering pre- and post-trial damages. Our jurisdiction is thus pursuant to 28 U.S.C. § 1292(a)(1).135
 Title 17 U.S.C. § 101 (1982), gives a more technical rendering, defining a computer program as "a set of statements or instructions to be used directly or indirectly in a computer in order to bring about a certain result."136
 More detailed descriptions of this process can be found in D. Bender, Computer Law — Software Protection § 2.06 (1985); Yohe, An Overview of Programming Tactics, 6 Computing Surveys 221 (1974).137
 Technically speaking, modules and subroutines are slightly different. Compare R. Andree, J. Andree & D. Andree, Computer Programming 336 (1973) (defining subroutines) with R. Coats, Software Engineering for Small Computers 12 (1983) (modules). For present purposes, however, they may be used synonymously as discrete parts of programs with readily identifiable tasks.138
 Elaine Whelan's material on the various elements, files and subroutines of the Dentalab system are voluminous, taking up over 200 pages of the record. See App. at 1222-1469. The material consisted of detailed outlines on how the program was to be structured.139
 The discussion in this paragraph draws heavily from Note, Copyright Protection of Computer Program Object Code, 96 Harv.L.Rev. 1723, 1724-25 (1983).140
 We ignore the distinction between "high level language" and "assembly language," see Note, 96 Harv.L.Rev. 1723, 1725 (1983), which is not relevant to the issues in this case. Both of these may be referred to as "source codes." See Apple Computer, Inc. v. Franklin Computer Corp, 714 F.2d 1240, 1243 (3d Cir.1983), cert. dismissed, 464 U.S. 1033, 104 S.Ct. 690, 79 L.Ed.2d 158 (1984).141
 The IBM Series One, for example, can read EDL but not BASIC; the IBM-PC can read BASIC, but not EDL.142
 The discussion assumes that the program is "compiled" or "assembled." If a program is "interpreted," then the source and object codes are joined in a single step. Whether a program is compiled or interpreted depends on the program and the machine on which it is run. The difference is not important in this case.143
 There are three other facets of program creation, debugging, documentation, and maintenance. Although none of these functions are at issue in this case, in the interest of completeness we shall describe them here. After the object code has been completed, the program must be "debugged" and documented. Debugging, or error removal, is frequently a lengthy process, for any moderately difficult task may require a fairly detailed and complex program. See D. Bender, supra, § 2.06[e]. The program demands arduous debugging not only because of its complexity, but also because of its delicacy. Even slight and perhaps obvious errors can hinder a program, for a computer has no way of recognizing errors. Like a perfect soldier, it takes instructions without questioning them.144
Documentation is the general term for the material that a programmer must give to a user to explain how the program runs. Programs frequently come with pamphlets that explain the program's powers and limitations. The documentation must anticipate as many potential questions and exigencies as the programmer can imagine the user will face because most people do not understand computers and programs fully, and it would therefore be very difficult for users to solve their problems themselves. Thus, proper documentation should "document everything, continually assuming [that the users] are going to have an attack of amnesia next week." Brown, Programming and Documenting Software Projects, 6 Computing Surveys 213, 219 (Dec.1974). See also Yohe, supra n. 14 at 221.145
Finally, programmers are also usually responsible for the maintenance of their programs. No matter how thorough the debugging and documentation, problems will likely arise as the user develops new needs for the program.146
The programmer, like a car manufacturer or dealer, must be prepared to fix latent bugs, adapt the program, or incur other so-called "life cycle" costs of maintenance.147
 The district court found, inter alia, that Rand Jaslow "had surreptitiously and without consent of either Strohl Systems or Whelan Associates obtained a copy of the [Dentalab] source code," 609 F.Supp. at 1314, and that he had "utilized the source code in his attempt to develop the IBM-PC Dentcom program," id. at 1321.148
 Although not an issue in this case, see infra n. 47, it is important to note that even the showing of substantial similarity is not dispositive, for it is still open to the alleged infringer to prove that his work is an original creation, see supra n. 7, or that the similarities between the works was not on account of copying but because both parties drew from common sources that were part of the public domain. The cause of the substantial similarity — legitimate or not — is a question of fact.149
 This circuit has once used the single substantial similarity inquiry advocated here in a computer copyright case. See Williams Electronics v. Arctic International, Inc., 685 F.2d 870, 876 n. 6 (3d Cir.1982) (finding substantial similarity in computer programs without mentioning the Arnstein test). Williams did not explain why it did not use the bifurcated Arnstein test, nor did it distinguish Universal Athletic Sales. To the extent that Williams did these things sub silentio, our holding today is merely a ratification of Williams on this point.150
 Because the first argument involves solely a question of law, our review is plenary. The second argument involves questions of fact, and we therefore apply the "clearly erroneous" standard of review. See Original Appalachian Artworks, Inc. v. Toy Loft, 684 F.2d 821, 825 n. 4 (11th Cir.1982); International Luggage Registry v. Avery Products, 541 F.2d 830, 831 (9th Cir.1976).151
 Professor Nimmer distinguishes two ways that one work might be substantially similar to another: comprehensive nonliteral similarity, and fragmented literal similarity. 3 Nimmer at § 13.03[A]. See also Warner Bros. v. American Broadcasting Cos., 720 F.2d 231, 240 (2d Cir.1983) (noting distinction); Smith v. Weinstein, 578 F.Supp. 1297, 1303 (S.D.N.Y.) (same), aff'd, 738 F.2d 419 (2d Cir.1984). The titles are suggestive of their meanings: comprehensive nonliteral similarity means "a similarity not just as to a particular line or paragraph or other minor segment, but [that] the fundamental essence or structure of one work is duplicated in another," 3 Nimmer at 13-20.1, while fragmented literal similarity means occasional, but not complete, word-for-word similarity, id. In Professor Nimmer's terminology, we are concerned here only with comprehensive nonliteral similarity.152
 Achieving the proper incentive has been a longstanding task of courts. See, e.g., Sayre v. Moore, 102 Eng.Rep. 138, 140 n. 6 (1785) (Lord Mansfield):153
[W]e must take care to guard against two extremes equally prejudicial; the one, that men of ability, who have employed their time for the service of the community, may not be deprived of their just merits, and the reward for their ingenuity and labour; the other, that the world may not be deprived of improvements, nor the progress of the arts be retarded.
See also Twentieth Century Music Corp. v. Aiken, 422 U.S. 151, 156, 95 S.Ct. 2040, 2044, 45 L.Ed.2d 84 (1975); Apple Computer, 714 F.2d at 1253 (Sloviter, J.) ("the line must be a pragmatic one, which also keeps in consideration `the preservation of the balance between competition and protection reflected in the patent and copyright laws.'" (quoting Herbert Rosenthal Jewelry Corp. v. Kalpakian, 446 F.2d 738, 742 (9th Cir.1971))).155
 This test is necessarily difficult to state, and it may be difficult to understand in the abstract. It will become more clear as we discuss and explain it in the textual discussion that follows this footnote. See also infra at 1242-44 (discussion of the copyrightability of file structures that raise many of the issues considered here). As will be seen, see infra at 1238-39, the idea of the Dentalab program was the efficient management of a dental laboratory (which presumably has significantly different requirements from those of other businesses). Because that idea could be accomplished in a number of different ways with a number of different structures, the structure of the Dentalab program is part of the program's expression, not its idea.156
 See Landsberg v. Scrabble Crossword Game Players, Inc., 736 F.2d 485, 489 (9th Cir.), cert. denied, ___ U.S. ___, 105 S.Ct. 513, 83 L.Ed.2d 403 (1984); See v. Durang, 711 F.2d at 143; Hoehling v. Universal City Studios, Inc., 618 F.2d 972, 979 (2d Cir.1980).157
 Hoehling, 618 F.2d at 979 (explaining the scenes a faire doctrine as follows: "Because it is virtually impossible to write about a particular historical era or fictional theme without employing certain `stock' or standard literary devices, we have held that scenes a faire are not copyrightable as a matter of law."); cf. Dymow v. Bolton, 11 F.2d at 691 ("[I]f the same idea can be expressed in a plurality of totally different manners, a plurality of copyrights may result ...").158
 As we discuss below, see infra n. 34, not all non-literal elements are essential to a given computer program.159
 Even if the product of the alleged infringer's efforts is a mixture of old and new elements, that would not protect it from the charge of infringement. Parodies, for example, mix copied elements with originality, yet they can violate the copyright of the work being parodied. See generally Note, The Parody Defense to Copyright Infringement: Productive Fair Use After Betamax, 97 Harv.L.Rev. 1395 (1984).160
 Long before the first computer, Sir Issac Newton humbly explained that "if [he] had seen farther than other men, it was because [he] had stood on the shoulders of giants."161
 We do not mean to imply that the idea or purpose behind every utilitarian or functional work will be precisely what it accomplishes, and that structure and organization will therefore always be part of the expression of such works. The idea or purpose behind a utilitarian work may be to accomplish a certain function in a certain way, see, e.g., Baker v. Selden, 101 U.S. at 100 (referring to Selden's book as explaining "a peculiar system of book-keeping"), and the structure or function of a program might be essential to that task. There is no suggestion in the record, however, that the purpose of the Dentalab program was anything so refined; it was simply to run a dental laboratory in an efficient way.162
 See also Mooers, Computer Software and Copyright, 7 Computing Surveys ___, 50 (March 1975) ("Also included in the `expression' is the sequence, choice, and arrangement of descriptive elements...."). Two commentators have criticized Synercom for its refusal to permit sequencing and ordering in the computer context to constitute expression. See Pierce, Copyright Protection for Computer Programs, 30 Copyright Law Symposium 1, 19 (1983) (Synercom "stands alone ... [in denying] copyright protection when the sequence and arrangement of data had been expressed by others in different ways." (footnote omitted)); Note, Defining the Scope of Copyright Protection for Computer Software, 38 Stan.L.Rev. 497, 525 (1986) (criticizing Synercom on the ground that "sequence and arrangement are expression that is separable from the underlying utilitarian purpose of the [input] formats, which is to enable the user to communicate with the computer program." (footnote omitted)). The notewriter concluded that "copyright law should ... recognize that organizing and connecting the modules and subroutines is a protectible act of authorship." Id. at 526.163
 It is not clear whether the end sought to be accomplished by the input formats involved in Synercom could be accomplished with different sequences and orders. Compare 462 F.Supp. at 1013 ("there are many ... possible choices of computer formats, and the decision among them [is] arbitrary") with id. at 1014 ("The `idea or principle' behind the forms in question, and the `method or system' involved in them, [are] no more or less than the formats."). Moreover, as noted above, the input formats involved in Synercom are not identical to the structures of computer programs that concern us here.164
 The defendants also rely on statements (not included in the CONTU Report) of individual members of the Commission and of testimony before the Commission. See Appellants' Br. at 16-17, 18-21. This extrinsic evidence is weak, however, and cannot outweigh the explicit statement of the CONTU Report itself.165
 Defendants' final argument as to the protectability of program structures is that the Copyright Office has taken the position that the defendants advocate here, and that as the Copyright Office is the agency responsible for the administration of the copyright laws, we should grant deference to its interpretation. In support of its position, the defendants refer us to the Copyright Office's Circular R61 (May 1983).166
EXTENT OF COPYRIGHT PROTECTION
Copyright protection extends to the literary or textual expression contained in the computer program. Copyright protection is not available for ideas, program logic, algorithms, systems, methods, concepts, or layouts.
Circular R61 (May, 1983). Copyright Office circulars are not technical documents, but are "intended to present simple explanations of the law," for lay persons. Declaration of Arthur J. Levine, former Assistant Chief of the Copyright Office Examining Division and member of CONTU Commission. It is therefore questionable whether the circular deserves great deference on a matter so complex as this one. At any rate, without analyzing the circular in depth — and its import is far from clear — we feel that the argument and evidence we have set forth in the text are sufficient support for our position and that to the extent the Copyright Office's circular differs, it should not be followed.168
 As will be seen below, defendants' argument here parallels their argument discussed in V.A. Defendants again rely on the idea-expression dichotomy and argue that computer files embody ideas and not expressions. The thrust of defendants' argument is that mere organization or ordering cannot be expression, but must be idea. Once again, we reject the argument. We separate the discussion here from the one in V.A. for two reasons. First, whereas defendants' first argument was that the structure of the whole program was classifiable as idea, not expression, the argument here is that a certain part of the program — the file structure — is idea, not expression. Thus, although the form of the arguments is the same, the subject is different. Second, in our analysis of the file structures, we are aided by the clear precedents and close analogy of blank forms, discussed infra. The law surrounding blank forms is particularly appropriate to the question of computer file structures.169
 See, e.g., Brown Instrument Co. v. Warner, 161 F.2d 910, 911 (D.C.Cir.), cert. denied, 332 U.S. 801, 68 S.Ct. 101, 92 L.Ed. 380 (1947); Taylor Instrument Companies v. Fawley-Brost Co., 139 F.2d 98, 100-01 (7th Cir.1943), cert. denied, 321 U.S. 785, 64 S.Ct. 782, 88 L.Ed. 1076 (1944).170
 See, e.g., Edwin K. Williams & Co. v. Edwin K. Williams & Co. — East, 542 F.2d 1053 (9th Cir.1976) (gas station account books held copyrightable), cert. denied, 433 U.S. 908, 97 S.Ct. 2973, 53 L.Ed.2d 1092 (1977); Baldwin Cooke Co. v. Keith Clarke, Inc., 383 F.Supp. 650, 652, 655 (N.D.Ill.) ("a combined calendar, appointment, diary and information book" is "much more than a mere diary," and is thus copyrightable), aff'd per curiam, 505 F.2d 1250 (7th Cir.1974); Harcourt Brace & World Inc. v. Graphic Controls Corp., 329 F.Supp. 517 (S.D.N.Y.1971) (answer sheets for recording multiple choice achievement and intelligence test answers held copyrightable). See also 1 Nimmer § 2.08[D]; id. § 2.18[C] (articulating and endorsing the "narrow" reading used by these courts, as contrasted by the "broad" reading illustrated in Brown, supra, and Taylor Instrument, supra); A. Latman, The Copyright Law 29-31 (5th ed.1979) (collecting cases).171
 It is unclear whether the Copyright Office's regulation would permit copyright protection for blank forms or would impose a per se rule against such protection. Title 37 C.F.R. § 202.1(c) (1985) denies copyright protection to172
Blank forms such as time cards, graph paper, account books, diaries, bank checks, scorecards, address books, report forms, order forms and the like, which are designed for recording information and do not in themselves convey information.
To the extent that the regulations do impose a per se rule against the copyrightability of blank forms, they have been criticized, see 1 Nimmer § 2.08[D]; id. at § 2.18[C], and have not been followed, see supra n. 41 (collecting cases).174
 Defendants' expert, Mr. Ness, testified that, given the problem to be solved, there were in fact few possible, efficient, file structures, and that the similarity in the programs' file structures was therefore neither surprising nor probative. See App. at 834-37. The district court apparently did not find Mr. Ness persuasive on this point, however, and we defer to the court's assessment. Had the defendants offered more evidence to support their position, our answer might have been different. It is true that for certain tasks there are only a very limited number of file structures available, and in such cases the structures might not be copyrightable and similarity of file structures might not be strongly probative of similarity of the program as a whole. We are simply not convinced that this is such a case.175
 Stern Electronics was simply explaining a party's decision to copyright the underlying program rather than the screen output. Midway Manufacturing's discussion was a part of its holding that a computer program for audiovisual games is copyrightable separately from the video display. Our analysis is perfectly consistent with this position. See infra at 1245.176
 Our holding that evidence of screen outputs may be admissible does not necessarily mean that such evidence would be alone sufficient to withstand motions of summary judgment or directed verdict.177
Judge Rosenn believes that ordinarily and in the circumstances of this case, screen outputs have no probative worth in determining whether one computer program is copied from another. Different program codes in different computer languages are capable of producing identical screen outputs. To the extent that the district court relied on the screen outputs as evidence of copying, he believes it erred. He concludes such error was harmless, however, in light of all the evidence of copying, the access to and use of the plaintiff's source code, the similarity in the structure of the programs and in the flow charts. This court will not reverse a district court's factual determination in a non-jury trial where there is sufficient evidence in the record to support it, other than the challenged evidence. DeLaval Turbine, Inc. v. West India Industries, Inc., 502 F.2d 259, 263-64 (3d Cir.1974).178
 Dr. Moore's notes comparing the two programs' modules were introduced as exhibits. His comparison of the order entry modules is characteristic of his comparisons of the other modules and is reprinted in Appendix A to this opinion. As we have suggested, this evidence is probative, not dispositive, of copyright infringements.179
 Of course structural similarities between two programs can also arise in completely legitimate ways — e.g., where the authors of the two programs have included subroutines from common, unprotected subroutine libraries, or where the authors of both programs have consulted common, public domain, reference books. There can be no bright line rules as to when similarities are evidence of infringement and when they are legitimate — that is a determination to be made by the trier of fact. See supra note 23. There is no suggestion in the present case that the similarities between Dentalab and Dentcom were the result of such common ground, however, and so the court's inference of copyright infringement from its finding of substantial similarity was correct.
450 U.S. 175 (1981)2
Supreme Court of United States.
Argued October 14, 1980.
Decided March 3, 1981.
CERTIORARI TO THE UNITED STATES COURT OF CUSTOMS AND PATENT APPEALS.7
 Deputy Solicitor General Wallace argued the cause for petitioner. With him on the briefs were Solicitor General McCree, Assistant Attorney General Litvack, Harriet S. Shapiro, Robert B. Nicholson, Frederic Freilicher, Joseph F. Nakamura, and Thomas E. Lynch.8
Robert E. Wichersham argued the cause for respondents. With him on the brief were Robert F. Hess, Jay M. Cantor, and Thomas M. Freiburger.9
We granted certiorari to determine whether a process for curing synthetic rubber which includes in several of its steps the use of a mathematical formula and a programmed digital computer is patentable subject matter under 35 U. S. C. § 101.11
The patent application at issue was filed by the respondents on August 6, 1975. The claimed invention is a process for molding raw, uncured synthetic rubber into cured precision products. The process uses a mold for precisely shaping the uncured material under heat and pressure and then curing the synthetic rubber in the mold so that the product will retain its shape and be functionally operative after the molding is completed.13
Respondents claim that their process ensures the production of molded articles which are properly cured. Achieving the perfect cure depends upon several factors including the thickness of the article to be molded, the temperature of the molding process, and the amount of time that the article is allowed to remain in the press. It is possible using well-known time, temperature, and cure relationships to calculate by means of the Arrhenius equation when to open the press  and remove the cured product. Nonetheless, according to the respondents, the industry has not been able to obtain uniformly accurate cures because the temperature of the molding press could not be precisely measured, thus making it difficult to do the necessary computations to determine cure time. Because the temperature inside the press has heretofore been viewed as an uncontrollable variable, the conventional industry practice has been to calculate the cure time as the shortest time in which all parts of the product will definitely be cured, assuming a reasonable amount of mold-opening time during loading and unloading. But the shortcoming of this practice is that operating with an uncontrollable variable inevitably led in some instances to overestimating the mold-opening time and overcuring the rubber, and in other instances to underestimating that time and undercuring the product.14
Respondents characterize their contribution to the art to reside in the process of constantly measuring the actual temperature inside the mold. These temperature measurements are then automatically fed into a computer which repeatedly recalculates the cure time by use of the Arrhenius equation.  When the recalculated time equals the actual time that has elapsed since the press was closed, the computer signals a device to open the press. According to the respondents, the continuous measuring of the temperature inside the mold cavity, the feeding of this information to a digital computer which constantly recalculates the cure time, and the signaling by the computer to open the press, are all new in the art.15
The patent examiner rejected the respondents' claims on the sole ground that they were drawn to nonstatutory subject matter under 35 U. S. C. § 101. He determined that those  steps in respondents' claims that are carried out by a computer under control of a stored program constituted nonstatutory subject matter under this Court's decision in Gottschalk v. Benson, 409 U. S. 63 (1972). The remaining steps—installing rubber in the press and the subsequent closing of the  press—were "conventional and necessary to the process and cannot be the basis of patentability." The examiner concluded that respondents' claims defined and sought protection of a computer program for operating a rubber-molding press.16
The Patent and Trademark Office Board of Appeals agreed with the examiner, but the Court of Customs and Patent Appeals reversed. In re Diehr, 602 F. 2d 892 (1979). The court noted that a claim drawn to subject matter otherwise statutory does not become nonstatutory because a computer is involved. The respondents' claims were not directed to a mathematical algorithm or an improved method of calculation but rather recited an improved process for molding rubber articles by solving a practical problem which had arisen in the molding of rubber products.17
The Commissioner of Patents and Trademarks sought certiorari arguing that the decision of the Court of Customs and Patent Appeals was inconsistent with prior decisions of this Court. Because of the importance of the question presented, we granted the writ. 445 U. S. 926 (1980).18
Last Term in Diamond v. Chakrabarty, 447 U. S. 303 (1980), this Court discussed the historical purposes of the patent laws and in particular 35 U. S. C. § 101. As in Chakrabarty, we must here construe 35 U. S. C. § 101 which provides:20
"Whoever invents or discovers any new and useful process, machine, manufacture, or composition of matter, or any new and useful improvement thereof, may obtain a patent therefor, subject to the conditions and requirements of this title."
 In cases of statutory construction, we begin with the language of the statute. Unless otherwise defined, "words will be interpreted as taking their ordinary, contemporary, common meaning," Perrin v. United States, 444 U. S. 37, 42 (1979), and, in dealing with the patent laws, we have more than once cautioned that "courts `should not read into the patent laws limitations and conditions which the legislature has not expressed.'" Diamond v. Chakrabarty, supra, at 308, quoting United States v. Dubilier Condenser Corp., 289 U. S. 178, 199 (1933).22
The Patent Act of 1793 defined statutory subject matter as "any new and useful art, machine, manufacture or composition of matter, or any new or useful improvement [thereof]." Act of Feb. 21, 1793, ch. 11, § 1, 1 Stat. 318. Not until the patent laws were recodified in 1952 did Congress replace the word "art" with the word "process." It is that latter word which we confront today, and in order to determine its meaning we may not be unmindful of the Committee Reports accompanying the 1952 Act which inform us that Congress intended statutory subject matter to "include anything under the sun that is made by man." S. Rep. No. 1979, 82d Cong., 2d Sess., 5 (1952); H. R. Rep. No. 1923, 82d Cong., 2d Sess., 6 (1952).23
Although the term "process" was not added to 35 U. S. C. § 101 until 1952, a process has historically enjoyed patent protection because it was considered a form of "art" as that term was used in the 1793 Act. In defining the nature of a patentable process, the Court stated:24
"That a process may be patentable, irrespective of the  particular form of the instrumentalities used, cannot be disputed. . . . A process is a mode of treatment of certain materials to produce a given result. It is an act, or a series of acts, performed upon the subject-matter to be transformed and reduced to a different state or thing. If new and useful, it is just as patentable as is a piece of machinery. In the language of the patent law, it is an art. The machinery pointed out as suitable to perform the process may or may not be new or patentable; whilst the process itself may be altogether new, and produce an entirely new result. The process requires  that certain things should be done with certain substances, and in a certain order; but the tools to be used in doing this may be of secondary consequence." Cochrane v. Deener, 94 U. S. 780, 787-788 (1877).
Analysis of the eligibility of a claim of patent protection for a "process" did not change with the addition of that term to § 101. Recently, in Gottschalk v. Benson, 409 U. S. 63 (1972), we repeated the above definition recited in Cochrane v. Deener, adding: "Transformation and reduction of an article `to a different state or thing' is the clue to the patentability of a process claim that does not include particular machines." 409 U. S., at 70.26
Analyzing respondents' claims according to the above statements from our cases, we think that a physical and chemical process for molding precision synthetic rubber products falls within the § 101 categories of possibly patentable subject matter. That respondents' claims involve the transformation of an article, in this case raw, uncured synthetic rubber, into a different state or thing cannot be disputed. The respondents' claims describe in detail a step-by-step method for accomplishing such, beginning with the loading of a mold with raw, uncured rubber and ending with the eventual opening of the press at the conclusion of the cure. Industrial processes such as this are the types which have historically been eligible to receive the protection of our patent laws.27
Our conclusion regarding respondents' claims is not altered by the fact that in several steps of the process a mathematical equation and a programmed digital computer are used. This Court has undoubtedly recognized limits to § 101 and every discovery is not embraced within the statutory terms. Excluded from such patent protection are laws of nature, natural phenomena, and abstract ideas. See Parker v. Flook, 437 U. S. 584 (1978); Gottschalk v. Benson, supra, at 67; Funk Bros. Seed Co. v. Kalo Inoculant Co., 333 U. S. 127, 130 (1948). "An idea of itself is not patentable," Rubber-Tip Pencil Co. v. Howard, 20 Wall. 498, 507 (1874). "A principle, in the abstract, is a fundamental truth; an original cause; a motive; these cannot be patented, as no one can claim in either of them an exclusive right." Le Roy v. Tatham, 14 How. 156, 175 (1853). Only last Term, we explained:29
"[A] new mineral discovered in the earth or a new plant found in the wild is not patentable subject matter. Likewise, Einstein could not patent his celebrated law that E=mc; nor could Newton have patented the law of gravity. Such discoveries are `manifestations of . . . nature, free to all men and reserved exclusively to none.'" Diamond v. Chakrabarty, 447 U. S., at 309, quoting Funk Bros. Seed Co. v. Kalo Inoculant Co., supra, at 130.
Our recent holdings in Gottschalk v. Benson, supra, and Parker v. Flook, supra, both of which are computer-related, stand for no more than these long-established principles. In Benson, we held unpatentable claims for an algorithm used to convert binary code decimal numbers to equivalent pure binary numbers. The sole practical application of the algorithm was in connection with the programming of a  general purpose digital computer. We defined "algorithm" as a "procedure for solving a given type of mathematical problem," and we concluded that such an algorithm, or mathematical formula, is like a law of nature, which cannot be the subject of a patent.31
Parker v. Flook, supra, presented a similar situation. The claims were drawn to a method for computing an "alarm limit." An "alarm limit" is simply a number and the Court concluded that the application sought to protect a formula for computing this number. Using this formula, the updated alarm limit could be calculated if several other variables were known. The application, however, did not purport to explain how these other variables were to be determined, nor  did it purport "to contain any disclosure relating to the chemical processes at work, the monitoring of process variables, or the means of setting off an alarm or adjusting an alarm system. All that it provides is a formula for computing an updated alarm limit." 437 U. S., at 586.32
In contrast, the respondents here do not seek to patent a mathematical formula. Instead, they seek patent protection for a process of curing synthetic rubber. Their process admittedly employs a well-known mathematical equation, but they do not seek to pre-empt the use of that equation. Rather, they seek only to foreclose from others the use of that equation in conjunction with all of the other steps in their claimed process. These include installing rubber in a press, closing the mold, constantly determining the temperature of the mold, constantly recalculating the appropriate cure time through the use of the formula and a digital computer, and automatically opening the press at the proper time. Obviously, one does not need a "computer" to cure natural or synthetic rubber, but if the computer use incorporated in the process patent significantly lessens the possibility of "overcuring" or "undercuring," the process as a whole does not thereby become unpatentable subject matter.33
Our earlier opinions lend support to our present conclusion that a claim drawn to subject matter otherwise statutory does not become nonstatutory simply because it uses a mathematical formula, computer program, or digital computer. In Gottschalk v. Benson we noted: "It is said that the decision precludes a patent for any program servicing a computer. We do not so hold." 409 U. S., at 71. Similarly, in Parker v. Flook we stated that "a process is not unpatentable simply because it contains a law of nature or a mathematical algorithm." 437 U. S., at 590. It is now commonplace that an application of a law of nature or mathematical formula to a known structure or process may well be deserving of patent protection. See, e. g., Funk Bros. Seed  Co. v. Kalo Inoculant Co., 333 U. S. 127 (1948); Eibel Process Co. v. Minnesota & Ontario Paper Co., 261 U. S. 45 (1923); Cochrane v. Deener, 94 U. S. 780 (1877); O'Reilly v. Morse, 15 How. 62 (1854); and Le Roy v. Tatham, 14 How. 156 (1853). As Justice Stone explained four decades ago:34
"While a scientific truth, or the mathematical expression of it, is not a patentable invention, a novel and useful structure created with the aid of knowledge of scientific truth may be." Mackay Radio & Telegraph Co. v. Radio Corp. of America, 306 U. S. 86, 94 (1939).
We think this statement in Mackay takes us a long way toward the correct answer in this case. Arrhenius' equation is not patentable in isolation, but when a process for curing rubber is devised which incorporates in it a more efficient solution of the equation, that process is at the very least not barred at the threshold by § 101.36
In determining the eligibility of respondents' claimed process for patent protection under § 101, their claims must be considered as a whole. It is inappropriate to dissect the claims into old and new elements and then to ignore the presence of the old elements in the analysis. This is particularly true in a process claim because a new combination of steps in a process may be patentable even though all the constituents of the combination were well known and in common use before the combination was made. The "novelty" of any element or steps in a process, or even of the  process itself, is of no relevance in determining whether the subject matter of a claim falls within the § 101 categories of possibly patentable subject matter.37
It has been urged that novelty is an appropriate consideration under § 101. Presumably, this argument results from the language in § 101 referring to any "new and useful" process, machine, etc. Section 101, however, is a general statement of the type of subject matter that is eligible for patent protection "subject to the conditions and requirements of this title." Specific conditions for patentability follow and § 102 covers in detail the conditions relating to novelty.  The question therefore of whether a particular invention is novel is "wholly apart from whether the invention falls into a category of statutory subject matter." In re Bergy, 596 F. 2d 952, 961 (CCPA 1979) (emphasis deleted). See also Nickola v. Peterson, 580 F. 2d 898 (CA6 1978). The legislative history of the 1952 Patent Act is in accord with this reasoning. The Senate Report stated:38
"Section 101 sets forth the subject matter that can be patented, `subject to the conditions and requirements of this title.' The conditions under which a patent may be obtained follow, and Section 102 covers the conditions relating to novelty." S. Rep. No. 1979, 82d Cong., 2d Sess., 5 (1952) (emphasis supplied).
It is later stated in the same Report:40
"Section 102, in general, may be said to describe the statutory novelty required for patentability, and includes,  in effect, an amplification and definition of `new' in section 101." Id., at 6.
Finally, it is stated in the "Revision Notes":42
"The corresponding section of [the] existing statute is split into two sections, section 101 relating to the subject matter for which patents may be obtained, and section 102 defining statutory novelty and stating other conditions for patentability." Id., at 17.
See also H. R. Rep. No. 1923, 82d Cong., 2d Sess., 6, 7, and 17 (1952).44
In this case, it may later be determined that the respondents' process is not deserving of patent protection because it fails to satisfy the statutory conditions of novelty under § 102 or nonobviousness under § 103. A rejection on either of these grounds does not affect the determination that respondents' claims recited subject matter which was eligible for patent protection under § 101.45
We have before us today only the question of whether respondents' claims fall within the § 101 categories of possibly patentable subject matter. We view respondents' claims as nothing more than a process for molding rubber products and not as an attempt to patent a mathematical formula. We recognize, of course, that when a claim recites a mathematical formula (or scientific principle or phenomenon of nature), an inquiry must be made into whether the claim is seeking patent protection for that formula in the abstract. A mathematical formula as such is not accorded the protection of our patent laws, Gottschalk v. Benson, 409 U. S. 63 (1972), and this principle cannot be circumvented by attempting to limit the use of the formula to a particular technological environment. Parker v. Flook, 437 U. S. 584 (1978). Similarly, insignificant postsolution activity will not transform  an unpatentable principle into a patentable process. Ibid. To hold otherwise would allow a competent draftsman to evade the recognized limitations on the type of subject matter eligible for patent protection. On the other hand, when a claim containing a mathematical formula implements or applies that formula in a structure or process which, when considered as a whole, is performing a function which the patent laws were designed to protect (e. g., transforming or reducing an article to a different state or thing), then the claim satisfies the requirements of § 101. Because we do not view respondents' claims as an attempt to patent a mathematical formula, but rather to be drawn to an industrial process  for the molding of rubber products, we affirm the judgment of the Court of Customs and Patent Appeals.47
It is so ordered.48
The starting point in the proper adjudication of patent litigation is an understanding of what the inventor claims  to have discovered. The Court's decision in this case rests on a misreading of the Diehr and Lutton patent application. Moreover, the Court has compounded its error by ignoring the critical distinction between the character of the subject matter that the inventor claims to be novel—the § 101 issue— and the question whether that subject matter is in fact novel—the § 102 issue.50
Before discussing the major flaws in the Court's opinion, a word of history may be helpful. As the Court recognized in Parker v. Flook, 437 U. S. 584, 595 (1978), the computer industry is relatively young. Although computer technology seems commonplace today, the first digital computer capable of utilizing stored programs was developed less than 30 years ago. Patent law developments in response to this new technology are of even more recent vintage. The subject of legal protection for computer programs did not begin to receive serious consideration until over a decade after completion of the first programmable digital computer. It was 1968 before  the federal courts squarely addressed the subject, and 1972 before this Court announced its first decision in the area.52
Prior to 1968, well-established principles of patent law probably would have prevented the issuance of a valid patent on almost any conceivable computer program. Under the "mental steps" doctrine, processes involving mental operations were considered unpatentable. See, e. g., In re Heritage, 32 C. C. P. A. (Pat.) 1170, 1173-1177, 150 F. 2d 554, 556-558 (1945); In re Shao Wen Yuan, 38 C. C. P. A. (Pat.) 967, 972-976, 188 F. 2d 377, 380-383 (1951). The mental-steps doctrine was based upon the familiar principle that a scientific concept or mere idea cannot be the subject of a valid patent. See In re Bolongaro, 20 C. C. P. A. (Pat.) 845, 846-847, 62 F. 2d 1059, 1060 (1933). The doctrine was regularly invoked to deny patents to inventions consisting primarily of mathematical formulae or methods of computation. It was also applied against patent claims in which a mental operation or mathematical computation was the sole novel element or inventive contribution; it was clear that patentability  could not be predicated upon a mental step. Under the "function of a machine" doctrine, a process which amounted to nothing more than a description of the function of a machine was unpatentable. This doctrine had its origin in several 19th-century decisions of this Court, and it had been consistently followed thereafter by the lower federal courts.  Finally, the definition of "process" announced by this Court in Cochrane v. Deener, 94 U. S. 780, 787-788 (1877), seemed to indicate that a patentable process must cause a physical transformation in the materials to which the process is applied. See ante, at 182-184.53
Concern with the patent system's ability to deal with rapidly changing technology in the computer and other fields led to the formation in 1965 of the President's Commission on the Patent System. After studying the question of computer program patentability, the Commission recommended that computer programs be expressly excluded from the coverage of the patent laws; this recommendation was based primarily upon the Patent Office's inability to deal with the administrative burden of examining program applications. At approximately the time that the Commission issued its report, the Patent Office published notice of its intention to prescribe guidelines for the examination of applications for patents on computer programs. See 829 Off. Gaz. Pat. Off. 865 (Aug. 16, 1966). Under the proposed guidelines, a computer program, whether claimed as an apparatus or as a process, was unpatentable. The Patent Office indicated, however,  that a programmed computer could be a component of a patentable process if combined with unobvious elements to produce a physical result. The Patent Office formally adopted the guidelines in 1968. See 33 Fed. Reg. 15609 (1968).54
The new guidelines were to have a short life. Beginning with two decisions in 1968, a dramatic change in the law as understood by the Court of Customs and Patent Appeals took place. By repudiating the well-settled "function of a machine" and "mental steps" doctrines, that court reinterpreted § 101 of the Patent Code to enlarge drastically the categories of patentable subject matter. This reinterpretation would lead to the conclusion that computer programs were within the categories of inventions to which Congress intended to extend patent protection.55
In In re Tarczy-Hornoch, 55 C. C. P. A. (Pat.) 1441, 397 F. 2d 856 (1968), a divided Court of Customs and Patent Appeals overruled the line of cases developing and applying the "function of a machine" doctrine. The majority acknowledged that the doctrine had originated with decisions of this Court and that the lower federal courts, including the Court of Customs and Patent Appeals, had consistently adhered to it during the preceding 70 years. Nonetheless, the court concluded that the doctrine rested on a misinterpretation of the precedents and that it was contrary to "the basic purposes of the patent system and productive of a range of undesirable results from the harshly inequitable to the silly." Id., at 1454, 397 F. 2d, at 867. Shortly thereafter, a similar  fate befell the "mental steps" doctrine. In In re Prater, 56 C. C. P. A. (Pat.) 1360, 415 F. 2d 1378 (1968), modified on rehearing, 56 C. C. A. P. (Pat.) 1381, 415 F. 2d 1393 (1969), the court found that the precedents on which that doctrine was based either were poorly reasoned or had been misinterpreted over the years. 56 C. C. P. A. (Pat.), at 1366-1372, 415 F. 2d, at 1382-1387. The court concluded that the fact that a process may be performed mentally should not foreclose patentability if the claims reveal that the process also may be performed without mental operations. Id., at 1374-1375, 415 F. 2d, at 1389. This aspect of the original Prater opinion was substantially undisturbed by the opinion issued after rehearing. However, the second Prater opinion clearly indicated that patent claims broad enough to encompass the operation of a programmed computer would not be rejected for lack of patentable subject matter. 56 C. C. P. A. (Pat.), at 1394, n. 29, 415 F. 2d, at 1403, n. 29.56
 The Court of Customs and Patent Appeals soon replaced the overruled doctrines with more expansive principles formulated with computer technology in mind. In In re Bernhart, 57 C. C. P. A. (Pat.) 737, 417 F. 2d 1395 (1969), the court reaffirmed Prater, and indicated that all that remained of the mental-steps doctrine was a prohibition on the granting of a patent that would confer a monopoly on all uses of a scientific principle or mathematical equation. Id., at 743, 417 F. 2d, at 1399. The court also announced that a computer programmed with a new and unobvious program was physically different from the same computer without that program; the programmed computer was a new machine or at least a new improvement over the unprogrammed computer. Id., at 744, 417 F. 2d, at 1400. Therefore, patent protection could be obtained for new computer programs if the patent claims were drafted in apparatus form.57
The Court of Customs and Patent Appeals turned its attention to process claims encompassing computer programs in In re Musgrave, 57 C. C. P. A. (Pat.) 1352, 431 F. 2d 882 (1970). In that case, the court emphasized the fact that Prater had done away with the mental-steps doctrine; in particular, the court rejected the Patent Office's continued reliance upon the "point of novelty" approach to claim analysis. Id., at 1362, 431 F. 2d, at 889. The court also announced a new standard for evaluating process claims under § 101: any sequence of operational steps was a patentable process under § 101 as long as it was within the "technological arts." Id., at 1366-1367, 431 F. 2d, at 893. This standard effectively disposed of any vestiges of the mental-steps doctrine remaining  after Prater and Bernhart. The "technological arts" standard was refined in In re Benson, 58 C. C. P. A. (Pat.) 1134, 441 F. 2d 682 (1971), in which the court held that computers, regardless of the uses to which they are put, are within the technological arts for purposes of § 101. Id., at 1142, 441 F. 2d, at 688.58
In re Benson, of course, was reversed by this Court in Gottschalk v. Benson, 409 U. S. 63 (1972). Justice Douglas' opinion for a unanimous Court made no reference to the lower court's rejection of the mental-steps doctrine or to the new technological-arts standard. Rather, the Court clearly held that new mathematical procedures that can be conducted in old computers, like mental processes and abstract intellectual concepts, see id., at 67, are not patentable processes within the meaning of § 101.59
 The Court of Customs and Patent Appeals had its first opportunity to interpret Benson in In re Christensen, 478 F. 2d 1392 (1973). In Christensen, the claimed invention was a method in which the only novel element was a mathematical formula. The court resurrected the point-of-novelty approach abandoned in Musgrave and held that a process claim in which the point of novelty was a mathematical equation to be solved as the final step of the process did not define patentable subject matter after Benson. 478 F. 2d, at 1394. Accordingly, the court affirmed the Patent Office Board of Appeals' rejection of the claims under § 101.60
The Court of Customs and Patent Appeals in subsequent cases began to narrow its interpretation of Benson. In In re Johnston, 502 F. 2d 765 (1974), the court held that a record-keeping machine system which comprised a programmed digital computer was patentable subject matter under § 101. Id., at 771. The majority dismissed Benson with the observation that Benson involved only process, not apparatus, claims. 502 F. 2d, at 771. Judge Rich dissented, arguing that to limit Benson only to process claims would make patentability turn upon the form in which a program invention was claimed. 502 F. 2d, at 773-774. The court again construed Benson as limited only to process claims in In re Noll, 545 F. 2d 141 (1976), cert. denied, 434 U. S. 875 (1977); apparatus claims were governed by the court's pre-Benson conclusion that a programmed computer was structurally different from the same computer without that particular program. 545 F. 2d, at 148. In dissent, Judge Lane, joined by Judge Rich, argued that Benson should be read as a general proscription of the patenting of computer programs regardless of the form of the claims. 545 F. 2d, at 151-152. Judge Lane's interpretation of Benson was rejected by the majority  in In re Chatfield, 545 F. 2d 152 (1976), cert. denied, 434 U. S. 875 (1977), decided on the same day as Noll. In that case, the court construed Benson to preclude the patenting of program inventions claimed as processes only where the claims would pre-empt all uses of an algorithm or mathematical formula. 545 F. 2d, at 156, 158-159. The dissenting judges argued, as they had in Noll, that Benson held that programs for general-purpose digital computers are not patentable subject matter. 545 F. 2d, at 161.61
Following Noll and Chatfield, the Court of Customs and Patent Appeals consistently interpreted Benson to preclude the patenting of a program-related process invention only when the claims, if allowed, would wholly pre-empt the algorithm itself. One of the cases adopting this view was In re Flook, 559 F. 2d 21 (1977), which was reversed in Parker v. Flook, 437 U. S. 584 (1978). Before this Court decided Flook, however, the lower court developed a two-step procedure for analyzing program-related inventions in light of Benson. In In re Freeman, 573 F. 2d 1237 (1978), the court held that such inventions must first be examined to determine whether a mathematical algorithm is directly or indirectly claimed; if an algorithm is recited, the court must then determine whether the claim would wholly pre-empt that algorithm. Only if a claim satisfied both inquiries was Benson considered applicable. 573 F. 2d, at 1245. See also In re Toma, 575 F. 2d 872, 877 (CCPA 1978).62
 In Flook, this Court clarified Benson in three significant respects. First, Flook held that the Benson rule of unpatentable subject matter was not limited, as the lower court believed, to claims which wholly pre-empted an algorithm or amounted to a patent on the algorithm itself. 437 U. S., at 589-590. Second, the Court made it clear that an improved method of calculation, even when employed as part of a physical process, is not patentable subject matter under § 101. Id., at 595, n. 18. Finally, the Court explained the correct procedure for analyzing a patent claim employing a mathematical algorithm. Under this procedure, the algorithm is treated for § 101 purposes as though it were a familiar part of the prior art; the claim is then examined to determine whether it discloses "some other inventive concept." Id., at 591-595.63
Although the Court of Customs and Patent Appeals in several post-Flook decisions held that program-related inventions were not patentable subject matter under § 101, see, e. g., In re Sarkar, 588 F. 2d 1330 (1978); In re Gelnovatch, 595 F. 2d 32 (1979), in general Flook was not enthusiastically received by that court. In In re Bergy, 596 F. 2d 952 (1979), the majority engaged in an extensive critique of Flook, concluding that this Court had erroneously commingled "distinct statutory provisions which are conceptually unrelated." 596 F. 2d, at 959. In subsequent cases, the court construed  Flook as resting on nothing more than the way in which the patent claims had been drafted, and it expressly declined to use the method of claim analysis spelled out in that decision. The Court of Customs and Patent Appeals has taken the position that, if an application is drafted in a way that discloses an entire process as novel, it defines patentable subject matter even if the only novel element that the inventor claims to have discovered is a new computer program. The court interpreted Flook in this manner in its opinion in this case. See In re Diehr, 602 F. 2d 982, 986-989 (1979). In my judgment, this reading of Flook—although entirely consistent with the lower court's expansive approach to § 101 during the past 12 years—trivializes the holding in Flook, the principle that underlies Benson, and the settled line of authority reviewed in those opinions.64
As I stated at the outset, the starting point in the proper adjudication of patent litigation is an understanding of what the inventor claims to have discovered. Indeed, the outcome of such litigation is often determined by the judge's understanding of the patent application. This is such a case.66
In the first sentence of its opinion, the Court states the question presented as "whether a process for curing synthetic rubber . . . is patentable subject matter." Ante, at 177. Of course, that question was effectively answered many years ago when Charles Goodyear obtained his patent on the vulcanization process. The patent application filed by Diehr  and Lutton, however, teaches nothing about the chemistry of the synthetic rubber-curing process, nothing about the raw materials to be used in curing synthetic rubber, nothing about the equipment to be used in the process, and nothing about the significance or effect of any process variable such as temperature, curing time, particular compositions of material, or mold configurations. In short, Diehr and Lutton do not claim to have discovered anything new about the process for curing synthetic rubber.67
As the Court reads the claims in the Diehr and Lutton patent application, the inventors' discovery is a method of constantly measuring the actual temperature inside a rubber molding press. As I read the claims, their discovery is an  improved method of calculating the time that the mold should remain closed during the curing process. If the Court's reading of the claims were correct, I would agree that they disclose patentable subject matter. On the other hand, if the Court accepted my reading, I feel confident that the case would be decided differently.68
There are three reasons why I cannot accept the Court's conclusion that Diehr and Lutton claim to have discovered a new method of constantly measuring the temperature inside a mold. First, there is not a word in the patent application that suggests that there is anything unusual about the temperature-reading devices used in this process—or indeed that any particular species of temperature-reading device should be used in it. Second, since devices for constantly  measuring actual temperatures—on a back porch, for example— have been familiar articles for quite some time, I find it difficult to believe that a patent application filed in 1975 was premised on the notion that a "process of constantly measuring the actual temperature" had just been discovered. Finally, the Patent and Trademark Office Board of Appeals expressly found that "the only difference between the conventional methods of operating a molding press and that claimed in [the] application rests in those steps of the claims which relate to the calculation incident to the solution of the mathematical problem or formula used to control the mold heater and the automatic opening of the press." This finding was not disturbed by the Court of Customs and Patent Appeals and is clearly correct.69
A fair reading of the entire patent application, as well as the specific claims, makes it perfectly clear that what Diehr and Lutton claim to have discovered is a method of using a digital computer to determine the amount of time that a rubber molding press should remain closed during the synthetic rubber-curing process. There is no suggestion that there is anything novel in the instrumentation of the mold, in actuating a timer when the press is closed, or in automatically opening the press when the computed time expires. Nor does the  application suggest that Diehr and Lutton have discovered anything about the temperatures in the mold or the amount of curing time that will produce the best cure. What they claim to have discovered, in essence, is a method of updating the original estimated curing time by repetitively recalculating that time pursuant to a well-known mathematical formula in response to variations in temperature within the mold. Their method of updating the curing time calculation is strikingly reminiscent of the method of updating alarm limits that Dale Flook sought to patent.70
Parker v. Flook, 437 U. S. 584 (1978), involved the use of a digital computer in connection with a catalytic conversion process. During the conversion process, variables such as temperature, pressure, and flow rates were constantly monitored and fed into the computer; in this case, temperature in the mold is the variable that is monitored and fed into the computer. In Flook, the digital computer repetitively recalculated the "alarm limit"—a number that might signal the need to terminate or modify the catalytic conversion process; in this case, the digital computer repetitively recalculates the correct curing time—a number that signals the time when the synthetic rubber molding press should open.71
The essence of the claimed discovery in both cases was an algorithm that could be programmed on a digital computer.  In Flook, the algorithm made use of multiple process variables; in this case, it makes use of only one. In Flook, the algorithm was expressed in a newly developed mathematical formula; in this case, the algorithm makes use of a well-known mathematical formula. Manifestly, neither of these differences can explain today's holding. What I believe  does explain today's holding is a misunderstanding of the applicants' claimed invention and a failure to recognize the critical difference between the "discovery" requirement in § 101 and the "novelty" requirement in § 102.72
The Court misapplies Parker v. Flook because, like the Court of Customs and Patent Appeals, it fails to understand or completely disregards the distinction between the subject matter of what the inventor claims to have discovered—the § 101 issue—and the question whether that claimed discovery is in fact novel—the § 102 issue. If there is not even a  claim that anything constituting patentable subject matter has been discovered, there is no occasion to address the novelty issue. Or, as was true in Flook, if the only concept that the inventor claims to have discovered is not patentable subject matter, § 101 requires that the application be rejected without reaching any issue under § 102; for it is irrelevant that unpatentable subject matter—in that case a formula for updating alarm limits—may in fact be novel.74
Proper analysis, therefore, must start with an understanding of what the inventor claims to have discovered—or phrased somewhat differently—what he considers his inventive concept to be. It seems clear to me that Diehr and  Lutton claim to have developed a new method of programming a digital computer in order to calculate—promptly and repeatedly—the correct curing time in a familiar process. In the § 101 analysis, we must assume that the sequence of steps in this programming method is novel, unobvious, and useful. The threshold question of whether such a method is patentable subject matter remains.75
If that method is regarded as an "algorithm" as that term was used in Gottschalk v. Benson, 409 U. S. 63 (1972), and in  Parker v. Flook, 437 U. S. 584 (1978), and if no other inventive concept is disclosed in the patent application, the question must be answered in the negative. In both Benson and Flook, the parties apparently agreed that the inventor's discovery was properly regarded as an algorithm; the holding that an algorithm was a "law of nature" that could not be  patented therefore determined that those discoveries were not patentable processes within the meaning of § 101.76
As the Court recognizes today, Flook also rejected the argument that patent protection was available if the inventor did not claim a monopoly on every conceivable use of the algorithm but instead limited his claims by describing a specific postsolution activity—in that case setting off an alarm in a catalytic conversion process. In its effort to distinguish Flook from the instant case, the Court characterizes that postsolution activity as "insignificant," ante, at 191, or as merely "token" activity, ante, at 192, n. 14. As a practical matter, however, the postsolution activity described in the Flook application was no less significant than the automatic opening of the curing mold involved in this case. For setting off an alarm limit at the appropriate time is surely as important to the safe and efficient operation of a catalytic conversion process as is actuating the mold-opening device in a synthetic rubber-curing process. In both cases, the post-solution activity is a significant part of the industrial process. But in neither case should that activity have any legal significance because it does not constitute a part of the inventive concept that the applicants claimed to have discovered.77
In Gottschalk v. Benson, we held that a program for the  solution by a digital computer of a mathematical problem was not a patentable process within the meaning of § 101. In Parker v. Flook, we further held that such a computer program could not be transformed into a patentable process by the addition of postsolution activity that was not claimed to be novel. That holding plainly requires the rejection of Claims 1 and 2 of the Diehr and Lutton application quoted in the Court's opinion. Ante, at 179-180, n. 5. In my opinion, it equally requires rejection of Claim 11 because the presolution activity described in that claim is admittedly a familiar part of the prior art.78
Even the Court does not suggest that the computer program developed by Diehr and Lutton is a patentable discovery. Accordingly, if we treat the program as though it were a familiar part of the prior art—as well-established precedent requires—it is absolutely clear that their application contains no claim of patentable invention. Their application was therefore properly rejected under § 101 by the Patent Office and the Board of Appeals.79
The broad question whether computer programs should be given patent protection involves policy considerations that  this Court is not authorized to address. See Gottschalk v. Benson, 409 U. S., at 72-73; Parker v. Flook, 437 U. S., at 595-596. As the numerous briefs amicus curiae filed in Gottschalk v. Benson, supra, Dann v. Johnston, 425 U. S. 219 (1976), Parker v. Flook, supra, and this case demonstrate, that question is not only difficult and important, but apparently also one that may be affected by institutional bias. In each of those cases, the spokesmen for the organized patent bar have uniformly favored patentability and industry representatives have taken positions properly motivated by their economic self-interest. Notwithstanding fervent argument that patent protection is essential for the growth of the software industry, commentators have noted that "this industry is growing by leaps and bounds without it." In addition, even  some commentators who believe that legal protection for computer programs is desirable have expressed doubts that the present patent system can provide the needed protection.81
Within the Federal Government, patterns of decision have also emerged. Gottschalk, Dann, Parker, and Diamond were not ordinary litigants—each was serving as Commissioner of Patents and Trademarks when he opposed the availability of patent protection for a program-related invention. No doubt each may have been motivated by a concern about the ability of the Patent Office to process effectively the flood of applications that would inevitably flow from a decision that computer programs are patentable. The consistent concern evidenced by the Commissioner of Patents and Trademarks and by the Board of Appeals of the Patent and Trademark Office has not been shared by the Court of Customs and Patent Appeals, which reversed the Board in Benson, Johnston, and Flook, and was in turn reversed by this Court in each of those cases.82
 Scholars have been critical of the work of both tribunals. Some of that criticism may stem from a conviction about the merits of the broad underlying policy question; such criticism may be put to one side. Other criticism, however, identifies two concerns to which federal judges have a duty to respond. First, the cases considering the patentability of program-related inventions do not establish rules that enable a conscientious patent lawyer to determine with a fair degree of accuracy which, if any, program-related inventions will be patentable. Second, the inclusion of the ambiguous concept of an "algorithm" within the "law of nature" category of unpatentable subject matter has given rise to the concern that almost any process might be so described and therefore held unpatentable.83
In my judgment, today's decision will aggravate the first concern and will not adequately allay the second. I believe both concerns would be better addressed by (1) an unequivocal holding that no program-related invention is a patentable process under § 101 unless it makes a contribution to the art that is not dependent entirely on the utilization of a computer, and (2) an unequivocal explanation that the term "algorithm" as used in this case, as in Benson and Flook, is synonymous with the term "computer program." Because  the invention claimed in the patent application at issue in this case makes no contribution to the art that is not entirely dependent upon the utilization of a computer in a familiar process, I would reverse the decision of the Court of Customs and Patent Appeals.84
 Edward S. Irons, Mary Helen Sears, and Robert P. Beshar filed a brief for National Semiconductor Corp. as amicus curiae urging reversal.85
Briefs of amici curiae urging affirmance were filed by Donald R. Dunner, Kenneth E. Kuffner, and Travis Gordon White for the American Patent Law Association, Inc.; by Morton C. Jacobs for Applied Data Research, Inc.; by William L. Mathis and Harold D. Messner for Chevron Research Co.; and by Reed C. Lawlor and James W. Geriak for the Los Angeles Patent Law Association.86
 A "cure" is obtained by mixing curing agents into the uncured polymer in advance of molding, and then applying heat over a period of time. If the synthetic rubber is cured for the right length of time at the right temperature, it becomes a usable product.87
 The equation is named after its discoverer Svante Arrhenius and has long been used to calculate the cure time in rubber-molding presses. The equation can be expressed as follows:88
wherein ln v is the natural logarithm of v, the total required cure time; C is the activation constant, a unique figure for each batch of each compound being molded, determined in accordance with rheometer measurements of each batch; Z is the temperature in the mold; and x is a constant dependent on the geometry of the particular mold in the press. A rheometer is an instrument to measure flow of viscous substances.90
 During the time a press is open for loading, it will cool. The longer it is open, the cooler it becomes and the longer it takes to reheat the press to the desired temperature range. Thus, the time necessary to raise the mold temperature to curing temperature is an unpredictable variable. The respondents claim to have overcome this problem by continuously measuring the actual temperature in the closed press through the use of a thermocouple.91
 We note that the petitioner does not seriously contest the respondents' assertions regarding the inability of the industry to obtain accurate cures on a uniform basis. See Brief for Petitioner 3.92
 Respondents' application contained 11 different claims. Three examples are claims 1, 2, and 11 which provide:93
"1. A method of operating a rubber-molding press for precision molded compounds with the aid of a digital computer, comprising:
"providing said computer with a data base for said press including at least,
"natural logarithm conversion data (ln),
"the activation energy constant (C) unique to each batch of said compound being molded, and
"a constant (x) dependent upon the geometry of the particular mold of the press,
"initiating an interval timer in said computer upon the closure of the press for monitoring the elapsed time of said closure,
"constantly determining the temperature (Z) of the mold at a location closely adjacent to the mold cavity in the press during molding,
"constantly providing the computer with the temperature (Z),
"repetitively calculating in the computer, at frequent intervals during each cure, the Arrhenius equation for reaction time during the cure, which is
"where v is the total required cure time,
"repetitively comparing in the computer at said frequent intervals during the cure each said calculation of the total required cure time calculated with the Arrhenius equation and said elapsed time, and
"opening the press automatically when a said comparison indicates equivalence.
"2. The method of claim 1 including measuring the activation energy constant for the compound being molded in the press with a rheometer and automatically updating said data base within the computer in the event of changes in the compound being molded in said press as measured by said rheometer.
"11. A method of manufacturing precision molded articles from selected synthetic rubber compounds in an openable rubber molding press having at least one heated precision mold, comprising:
"(a) heating said mold to a temperature range approximating a pre-determined rubber curing temperature,
"(b) installing prepared unmolded synthetic rubber of a known compound in a molding cavity of predetermined geometry as defined by said mold,
"(c) closing said press to mold said rubber to occupy said cavity in conformance with the contour of said mold and to cure said rubber by transfer of heat thereto from said mold,
"(d) initiating an interval timer upon the closure of said press for monitoring the elapsed time of said closure,
"(e) heating said mold during said closure to maintain the temperature thereof within said range approximating said rubber curing temperature,
"(f) constantly determining the temperature of said mold at a location closely adjacent said cavity thereof throughout closure of said press,
"(g) repetitively calculating at frequent periodic intervals throughout closure of said press the Arrhenius equation for reaction time of said rubber to determine total required cure time v as follows:
"wherein c is an activation energy constant determined for said rubber being molded and cured in said press, z is the temperature of said mold at the time of each calculation of said Arrhenius equation, and x is a constant which is a function of said predetermined geometry of said mold,
"(h) for each repetition of calculation of said Arrhenius equation herein, comparing the resultant calculated total required cure time with the monitored elapsed time measured by said interval timer,
"(i) opening said press when a said comparison of calculated total required cure time and monitored elapsed time indicates equivalence, and
"(j) removing from said mold the resultant precision molded and cured rubber article."
 The word "process" is defined in 35 U. S. C. § 100 (b):95
"The term `process' means process, art or method, and includes a new use of a known process, machine, manufacture, composition of matter, or material."
 In Corning v. Burden, 15 How. 252, 267-268 (1854), this Court explained:97
"A process, eo nomine, is not made the subject of a patent in our act of congress. It is included under the general term `useful art.' An art may require one or more processes or machines in order to produce a certain result or manufacture. The term machine includes every mechanical device or combination of mechanical powers and devices to perform some function and produce a certain effect or result. But where the result or effect is produced by chemical action, by the operation or application of some element or power of nature, or of one substance to another, such modes, methods, or operations, are called processes. A new process is usually the result of discovery; a machine, of invention. The arts of tanning, dyeing, making water-proof cloth, vulcanizing India rubber, smelting ores, and numerous others, are usually carried on by processes as distinguished from machines. One may discover a new and useful improvement in the process of tanning, dyeing, &c.;, irrespective of any particular form of machinery or mechanical device. And another may invent a labor-saving machine by which this operation or process may be performed, and each may be entitled to his patent. As, for instance, A has discovered that by exposing India rubber to a certain degree of heat, in mixture or connection with certain metalic salts, he can produce a valuable product, or manufacture; he is entitled to a patent for his discovery, as a process or improvement in the art, irrespective of any machine or mechanical device. B, on the contrary, may invent a new furnace or stove, or steam apparatus, by which this process may be carried on with much saving of labor, and expense of fuel; and he will be entitled to a patent for his machine, as an improvement in the art. Yet A could not have a patent for a machine, or B for a process; but each would have a patent for the means or method of producing a certain result, or effect, and not for the result or effect produced. It is for the discovery or invention of some practical method or means of producing a beneficial result or effect, that a patent is granted, and not for the result or effect itself. It is when the term process is used to represent the means or method of producing a result that it is patentable, and it will include all methods or means which are not effected by mechanism or mechanical combinations."
 We note that as early as 1854 this Court approvingly referred to patent eligibility of processes for curing rubber. See id., at 267; n. 7, supra. In Tilghman v. Proctor, 102 U. S. 707 (1881), we referred to the original patent Charles Goodyear received on his process for "vulcanizing" or curing rubber. We stated:99
"That a patent can be granted for a process, there can be no doubt. The patent law is not confined to new machines and new compositions of matter, but extends to any new and useful art or manufacture. A manufacturing process is clearly an art, within the meaning of the law. Good-year's patent was for a process, namely, the process of vulcanizing india-rubber by subjecting it to a high degree of heat when mixed with sulphur and a mineral salt. The apparatus for performing the process was not patented, and was not material. The patent pointed out how the process could be effected, and that was deemed sufficient." Id., at 722.
 The term "algorithm" is subject to a variety of definitions. The petitioner defines the term to mean:101
"`1. A fixed step-by-step procedure for accomplishing a given result; usually a simplified procedure for solving a complex problem, also a full statement of a finite number of steps. 2. A defined process or set of rules that leads [sic] and assures development of a desired output from a given input. A sequence of formulas and/or algebraic/logical steps to calculate or determine a given task; processing rules.'" Brief for Petitioner in Diamond v. Bradley, O. T. 1980, No. 79-855, p. 6, n. 12, quoting C. Sippl & R. Sippl, Computer Dictionary and Handbook 23 (2d ed. 1972).
This definition is significantly broader than the definition this Court employed in Benson and Flook. Our previous decisions regarding the patentability of "algorithms" are necessarily limited to the more narrow definition employed by the Court, and we do not pass judgment on whether processes falling outside the definition previously used by this Court, but within the definition offered by the petitioner, would be patentable subject matter.103
 As we explained in Flook, in order for an operator using the formula to calculate an updated alarm limit the operator would need to know the original alarm base, the appropriate margin of safety, the time interval that should elapse between each updating, the current temperature (or other process variable), and the appropriate weighing factor to be used to average the alarm base and the current temperature. 437 U. S., at 586. The patent application did not "explain how to select the approximate margin of safety, the weighing factor, or any of the other variables." Ibid.104
 We noted in Funk Bros. Seed Co. v. Kalo Inoculant Co., 333 U. S. 127, 130 (1948):105
"He who discovers a hitherto unknown phenomenon of nature has no claim to a monopoly of it which the law recognizes. If there is to be invention from such a discovery, it must come from the application of the law of nature to a new and useful end."
Although we were dealing with a "product" claim in Funk Bros., the same principle applies to a process claim. Gottschalk v. Benson, 409 U. S. 63, 68 (1972).107
 It is argued that the procedure of dissecting a claim into old and new elements is mandated by our decision in Flook which noted that a mathematical algorithm must be assumed to be within the "prior art." It is from this language that the petitioner premises his argument that if everything other than the algorithm is determined to be old in the art, then the claim cannot recite statutory subject matter. The fallacy in this argument is that we did not hold in Flook that the mathematical algorithm could not be considered at all when making the § 101 determination. To accept the analysis proffered by the petitioner would, if carried to its extreme, make all inventions unpatentable because all inventions can be reduced to underlying principles of nature which, once known, make their implementation obvious. The analysis suggested by the petitioner would also undermine our earlier decisions regarding the criteria to consider in determining the eligibility of a process for patent protection. See, e. g., Gottschalk v. Benson, supra; and Cochrane v. Deener, 94 U. S. 780 (1877).108
 Section 102 is titled "Conditions for patentability; novelty and loss of right to patent," and provides:109
"A person shall be entitled to a patent unless—
"(a) the invention was known or used by others in this country, or patented or described in a printed publication in this or a foreign country, before the invention thereof by the applicant for patent, or
"(b) the invention was patented or described in a printed publication in this or a foreign country or in public use or on sale in this country, more than one year prior to the date of the application for patent in the United States, or
"(c) he has abandoned the invention, or
"(d) the invention was first patented or caused to be patented, or was the subject of an inventor's certificate, by the applicant or his legal representatives or assigns in a foreign country prior to the date of the application for patent in this country on an application for patent or inventor's certificate filed more than twelve months before the filing of the application in the United States, or
"(e) the invention was described in a patent granted on an application for patent by another filed in the United States before the invention thereof by the applicant for patent, or on an international application by another who has fulfilled the requirements of paragraphs (1), (2), and (4) of section 371 (c) of this title before the invention thereof by the applicant for patent, or
"(f) he did not himself invent the subject matter sought to be patented, or
"(g) before the applicant's invention thereof the invention was made in this country by another who had not abandoned, suppressed, or concealed it. In determining priority of invention there shall be considered not only the respective dates of conception and reduction to practice of the invention, but also the reasonable diligence of one who was first to conceive and last to reduce to practice, from a time prior to conception by the other."
 Arguably, the claims in Flook did more than present a mathematical formula. The claims also solved the calculation in order to produce a new number or "alarm limit" and then replaced the old number with the number newly produced. The claims covered all uses of the formula in processes "comprising the catalytic chemical conversion of hydrocarbons." There are numerous such processes in the petrochemical and oil refinery industries and the claims therefore covered a broad range of potential uses. 437 U. S., at 586. The claims, however, did not cover every conceivable application of the formula. We rejected in Flook the argument that because all possible uses of the mathematical formula were not pre-empted, the claim should be eligible for patent protection. Our reasoning in Flook is in no way inconsistent with our reasoning here. A mathematical formula does not suddenly become patentable subject matter simply by having the applicant acquiesce to limiting the reach of the patent for the formula to a particular technological use. A mathematical formula in the abstract is nonstatutory subject matter regardless of whether the patent is intended to cover all uses of the formula or only limited uses. Similarly, a mathematical formula does not become patentable subject matter merely by including in the claim for the formula token postsolution activity such as the type claimed in Flook. We were careful to note in Flook that the patent application did not purport to explain how the variables used in the formula were to be selected, nor did the application contain any disclosure relating to chemical processes at work or the means of setting off an alarm or adjusting the alarm limit. Ibid. All the application provided was a "formula for computing an updated alarm limit." Ibid.111
 The dissent's analysis rises and falls on its characterization of respondents' claims as presenting nothing more than "an improved method of calculating the time that the mold should remain closed during the curing process." Post, at 206-207. The dissent states that respondents claim only to have developed "a new method of programming a digital computer in order to calculate—promptly and repeatedly—the correct curing time in a familiar process." Post, at 213. Respondents' claims, however, are not limited to the isolated step of "programming a digital computer." Rather, respondents' claims describe a process of curing rubber beginning with the loading of the mold and ending with the opening of the press and the production of a synthetic rubber product that has been perfectly cured—a result heretofore unknown in the art. See n. 5, supra. The fact that one or more of the steps in respondents' process may not, in isolation, be novel or independently eligible for patent protection is irrelevant to the question of whether the claims as a whole recite subject matter eligible for patent protection under § 101. As we explained when discussing machine patents in Deepsouth Packing Co. v. Laitram Corp., 406 U. S. 518 (1972):112
"The patents were warranted not by the novelty of their elements but by the novelty of the combination they represented. Invention was recognized because Laitram's assignors combined ordinary elements in an extraordinary way—a novel union of old means was designed to achieve new ends. Thus, for both inventions `the whole in some way exceed[ed] the sum of its parts.' Great A. & P. Tea Co. v. Supermarket Equipment Corp., 340 U. S. 147, 152 (1950)." Id., at 521-522 (footnote omitted).
In order for the dissent to reach its conclusion it is necessary for it to read out of respondents' patent application all the steps in the claimed process which it determined were not novel or "inventive." That is not the purpose of the § 101 inquiry and conflicts with the proposition recited above that a claimed invention may be entitled to patent protection even though some or all of its elements are not "novel."114
 ENIAC, the first general purpose electronic digital computer, was built in 1946. Unlike modern computers, this machine was externally programmed; its circuitry had to be manually rewired each time it was used to perform a new task. See Gemignani, Legal Protection for Computer Software: The View From `79, 7 Rutgers J. Computers, Tech. & L. 269, 270 (1980). In 1952, a group of scientists at the Institute for Advanced Study completed MANIAC I, the first digital computer capable of operating upon stored programs, as opposed to hard-wired circuitry. See Ulam, Computers, 211 Scientific American 203 (1964).115
 The subject received some scholarly attention prior to 1964. See, e. g., Seidel, Antitrust, Patent and Copyright Law Implications of Computer Technology, 44 J. Pat. Off. Soc. 116 (1962); Comment, The Patentability of Computer Programs, 38 N. Y. U. L. Rev. 891 (1963). In 1964, the Copyright Office began registering computer programs. See 11 Copyright Soc. Bull. 361 (1964); Davis, Computer Programs and Subject Matter Patentability, 6 Rutgers J. Computers, Tech. & L. 1, 5 (1977). Also in 1964, the Patent Office Board of Appeals issued what appears to be the first published opinion concerning the patentability of a computer-related invention. See Ex parte King, 146 USPQ 590.116
 In re Prater, 56 C. C. P. A. (Pat.) 1360, 415 F. 2d 1378 (1968), modified on rehearing, 56 C. C. P. A. (Pat.) 1381, 415 F. 2d 1393 (1969), is generally identified as the first significant judicial decision to consider the subject-matter patentability of computer program-related inventions. The Court of Customs and Patent Appeals earlier decided In re Naquin, 55 C. C. P. A. (Pat.) 1428, 398 F. 2d 863 (1968), in which it rejected a challenge to an application for a patent on a program-related invention on grounds of inadequate disclosure under § 112.117
 See Gottschalk v. Benson, 409 U. S. 63 (1972).118
 See also Novick & Wallenstein, The Algorithm and Computer Software Patentability: A Scientific View of a Legal Problem, 7 Rutgers J. Computers, Tech. & L. 313, 316-317 (1980).119
 See, e. g., Don Lee, Inc. v. Walker, 61 F. 2d 58, 67 (CA9 1932); In re Bolongaro, 20 C. C. P. A. (Pat.) 845, 846-847, 62 F. 2d 1059, 1060 (1933); In re Shao Wen Yuan, 38 C. C. P. A. (Pat.) 967, 969-972, 188 F. 2d 377, 379-380 (1951); Lyman v. Ladd, 120 U. S. App. D. C. 388, 389, 347 F. 2d 482, 483 (1965).120
 See, e. g., In re Cooper, 30 C. C. P. A. (Pat.) 946, 949, 134 F. 2d 630, 632 (1943); Halliburton Oil Well Cementing Co. v. Walker, 146 F. 2d 817, 821, 823 (CA9 1944), rev'd on other grounds, 329 U. S. 1 (1946); In re Heritage, 32 C. C. P. A. (Pat.) 1170, 1173-1177, 150 F. 2d 554, 556-558 (1945); In re Abrams, 38 C. C. P. A. (Pat.) 945, 950-953, 188 F. 2d 165, 168-170 (1951); In re Shao Wen Yuan, supra, at 975-976, 188 F. 2d, at 383; In re Lundberg, 39 C. C. P. A. (Pat.) 971, 975, 197 F. 2d 336, 339 (1952); In re Venner, 46 C. C. P. A. (Pat.) 754, 758-759, 262 F. 2d 91, 95 (1958).121
 The "function of a machine" doctrine is generally traced to Corning v. Burden, 15 How. 252, 268 (1854), in which the Court stated: "[I]t is well settled that a man cannot have a patent for the function or abstract effect of a machine, but only for the machine which produces it." The doctrine was subsequently reaffirmed on several occasions. See, e. g., Risdon Iron & Locomotive Works v. Medart, 158 U. S. 68, 78-79, 84 (1895); Westinghouse v. Boyden Power Brake Co., 170 U. S. 537, 554-557 (1898); Busch v. Jones, 184 U. S. 598, 607 (1902); Expanded Metal Co. v. Bradford, 214 U. S. 366, 383 (1909).122
 See, e. g., In re Weston, 17 App. D. C. 431, 436-442 (1901); Chisholm-Ryder Co. v. Buck, 65 F. 2d 735, 736 (CA4 1933); In re Ernst, 21 C. C. P. A. (Pat.) 1235, 1238-1240, 71 F. 2d 169, 171-172 (1934); In re McCurdy, 22 C. C. P. A. (Pat.) 1140, 1142-1145, 76 F. 2d 400, 402-403, (1935); In re Parker, 23 C. C. P. A. (Pat.) 721, 722-725, 79 F. 2d 908, 909-910 (1935); Black-Clawson Co. v. Centrifugal Engineering & Patents Corp., 83 F. 2d 116, 119-120 (CA6), cert. denied, 299 U. S. 554 (1936); In re Wadman, 25 C. C. P. A. (Pat.) 936, 943-944, 94 F. 2d 993, 998 (1938); In re Mead, 29 C. C. P. A. (Pat.) 1001, 1004, 127 F. 2d 302, 304 (1942); In re Solakian, 33 C. C. P. A. (Pat.) 1054, 1059, 155 F. 2d 404, 407 (1946); In re Middleton, 35 C. C. P. A. (Pat.) 1166, 1167-1168, 167 F. 2d 1012, 1013-1014 (1948); In re Nichols, 36 C. C. P. A. (Pat.) 759, 762-763, 171 F. 2d 300, 302-303 (1948); In re Ashbaugh, 36 C. C. P. A. (Pat.) 902, 904-905, 173 F. 2d 273, 274-275 (1949); In re Horvath, 41 C. C. P. A. (Pat.) 844, 849-851, 211 F. 2d 604, 607-608 (1954); In re Gartner, 42 C. C. P. A. (Pat.) 1022, 1025-1026, 223 F. 2d 502, 504 (1955).123
 The Commission's report contained the following evaluation of the current state of the law with respect to computer program patentability:124
"Uncertainty now exists as to whether the statute permits a valid patent to be granted on programs. Direct attempts to patent programs have been rejected on the ground of nonstatutory subject matter. Indirect attempts to obtain patents and avoid the rejection, by drafting claims as a process, or a machine or components thereof programmed in a given manner, rather than as a program itself, have confused the issue further and should not be permitted." Report of the President's Commission on the Patent System, "To Promote the Progress of . . . Useful Arts" in an Age of Exploding Technology 14 (1966).
 The Patent Office guidelines were based primarily upon the mental-steps doctrine and the Cochrane v. Deener, 94 U. S. 780 (1877), definition of "process." See 829 Off. Gaz. Pat. Off. 865 (Aug. 16, 1966); 33 Fed. Reg. 15609 (1968).126
 Judge Kirkpatrick, joined by Chief Judge Worley, wrote a vigorous dissent objecting to the majority's decision to abandon "a rule which is about as solidly established as any rule of the patent law." 55 C. C. P. A. (Pat.), at 1457, 397 F. 2d, at 868. Unlike the majority, the dissenting judges did not consider the doctrine inequitable or silly, and they observed that it had functioned in a satisfactory manner in the past. Id., at 1457-1458, 397 F. 2d, at 869. In addition, they considered the doctrine to be so well established that it had been adopted by implication in the Patent Act of 1952. Id., at 1458, 397 F. 2d, at 869.127
 In Prater, the patent application claimed an improved method for processing spectrographic data. The method analyzed conventionally obtained data by using well-known equations. The inventors had discovered a particular mathematical characteristic of the equations which enabled them to select the specific subset of equations that would yield optimum results. The application disclosed an analog computer as the preferred embodiment of the invention, but indicated that a programmed digital computer could also be used. 56 C. C. P. A. (Pat.), at 1361-1363, 415 F. 2d, at 1379-1380. The Patent Office had rejected the process claims on a mental-steps theory because the only novel aspect of the claimed method was the discovery of an unpatentable mathematical principle. The apparatus claim was rejected essentially because, when the mathematical principle was assumed to be within the prior art, the claim disclosed no invention entitled to patent protection. Id., at 1364-1365, 1375, 415 F. 2d, at 1381, 1399.128
 It is interesting to note that the Court of Customs and Patent Appeals in the second Prater opinion expressly rejected the Patent Office's procedure for analyzing the apparatus claim pursuant to which the mathematical principle was treated as though it were within the prior art. 56 C. C. P. A. (Pat.), at 1397, 415 F. 2d, at 1405-1406. This precise procedure, of course, was later employed by this Court in Parker v. Flook, 437 U. S. 584 (1978).129
 Under the "point of novelty" approach, if the novelty or advancement in the art claimed by the inventor resided solely in a step of the process embodying a mental operation or other unpatentable element, the claim was rejected under § 101 as being directed to nonstatutory subject matter. See Blumenthal & Riter, Statutory or Non-Statutory?: An Analysis of the Patentability of Computer Related Inventions, 62 J. Pat. Off. Soc. 454, 457, 461, 470 (1980).130
 The author of the second Prater opinion, Judge Baldwin, disagreed with the Musgrave "technological arts" standard for process claims. He described that standard as "a major and radical shift in this area of the law." 57 C. C. P. A. (Pat.), at 1367, 431 F. 2d, at 893-894. As Judge Baldwin read the majority opinion, claims drawn solely to purely mental processes were now entitled to patent protection. Id., at 1369, 431 F. 2d, at 895-896. Judge Baldwin's understanding of Musgrave seems to have been confirmed in In re Foster, 58 C. C. P. A. (Pat.) 1001, 1004-1005, 438 F. 2d 1011, 1014-1015 (1971).131
 In the interval between the two Benson decisions, the Court of Customs and Patent Appeals decided several cases in which it addressed the patentability of computer-related inventions. In In re McIlroy, 58 C. C. P. A. (Pat.) 1249, 442 F. 2d 1397 (1971), and In re Waldbaum, 59 C. C. P. A. (Pat.) 940, 457 F. 2d 997 (1972), the court relied primarily upon Musgrave and Benson. In In re Ghiron, 58 C. C. P. A. (Pat.) 1207, 442 F. 2d 985 (1971), the court reaffirmed Tarczy-Hornoch's rejection of the "function of a machine" doctrine.132
 Although the Court did not discuss the mental-steps doctrine in Benson, some commentators have suggested that the Court implicitly relied upon the doctrine in that case. See, e. g., Davis, supra n. 2, at 14, and n. 92. Other commentators have observed that the Court's analysis in Benson was entirely consistent with the mental-steps doctrine. See, e. g., Comment, Computer Program Classification: A Limitation on Program Patentability as a Process, 53 Or. L. Rev. 501, 517-518, n. 132 (1974).133
 The decision of the Court of Customs and Patent Appeals was reversed by this Court on other grounds in Dann v. Johnston, 425 U. S. 219 (1976).134
 In addition to interpreting Benson, the majority also maintained that Christensen, despite its point-of-novelty language, had not signalled a return to that form of claim analysis. 545 F. 2d, at 158. The court would reaffirm this proposition consistently thereafter. See, e. g., In re de Castelet, 562 F. 2d 1236, 1240 (1977); In re Richman, 563 F. 2d 1026, 1029-1030 (1977); In re Freeman, 573 F. 2d 1237, 1243-1244 (1978); In re Toma, 575 F. 2d 872, 876 (1978); In re Walter, 618 F. 2d 758, 766-767 (1980).135
 See also In re Deutsch, 553 F. 2d 689, 692-693 (CCPA 1977); In re Waldbaum, 559 F. 2d 611, 616-617 (CCPA 1977); In re de Castelet, supra, at 1243-1245.136
 This form of claim analysis did not originate with Flook. Rather, the Court derived it from the landmark decision of O'Reilly v. Morse, 15 How. 62, 115 (1854). In addition, this analysis is functionally the same as the point-of-novelty analysis used in conjunction with the mental-steps doctrine. In fact, the Patent Office in the past occasionally phrased its mental-steps rejections in essentially the terms later employed in Flook. See nn. 13-15, supra. See generally Comment, 35 U. S. C. 101 Claim Analysis—The Point of Novelty Approach, 62 J. Pat. Off. Soc. 521 (1980).137
 The Court of Customs and Patent Appeals suggested that the cause of this Court's error was the argument presented by the Solicitor General in Flook. According to the majority, the Solicitor General's briefs "badly, and with a seeming sense of purpose" confused the statutory requirements. 596 F. 2d, at 962. The court went on to describe part of the Solicitor General's argument in Flook as "subversive nonsense." 596 F. 2d, at 963.138
 See, e. g., In re Johnson, 589 F. 2d 1070 (1978); In re Phillips, 608 F. 2d 879 (1979); In re Sherwood, 613 F. 2d 809 (1980), cert. pending, No. 79-1941.139
 In an opinion written over a century ago, the Court noted:140
"A manufacturing process is clearly an art, within the meaning of the law. Goodyear's patent was for a process, namely, the process of vulcanizing india-rubber by subjecting it to a high degree of heat when mixed with sulphur and a mineral salt.
"The mixing of certain substances together, or the heating of a substance to a certain temperature, is a process." Tilghman v. Proctor, 102 U. S. 707, 722, 728 (1881).
See also Corning v. Burden, 15 How. 252, 267 (1854). Modern rubber curing methods apparently still are based in substantial part upon the concept discovered by Goodyear:142
"Since the day 120 years ago when Goodyear first heated a mixture of rubber and sulphur on a domestic stove and so discovered vulcanisation, this action of heat and sulphur has remained the standard method of converting crude rubber, with all its limitations, into a commercially usable product, giving it the qualities of resistance to heat and cold in addition to considerable mechanical strength.
"Goodyear also conjured up the word `cure' for vulcanisation, and this has become the recognised term in production circles." Mernagh, Practical Vulcanisation, in The Applied Science of Rubber 1053 (W. Naunton ed. 1961).
See generally Kimmich, Making Rubber Products for Engineering Uses, in Engineering Uses of Rubber 18, 28-34 (A. McPherson & A. Klemin eds. 1956)144
 "Respondents characterize their contribution to the art to reside in the process of constantly measuring the actual temperature inside the mold." See ante, at 178.145
 Claim 1 is quoted in full in n. 5 of the Court's opinion, ante, at 179. It describes a "method of operating a rubber-molding press for precision molded compounds with the aid of a digital computer." As the Court of Customs and Patent Appeals noted, the improvement claimed in the application consists of "opening the mold at precisely the correct time rather than at a time which has been determined by approximation or guesswork." In re Diehr, 602 F. 2d 982, 988 (1979).146
 In the portion of the patent application entitled "Abstract of the Disclosure," the following reference to monitoring the temperature is found:147
"An interval timer starts running from the time of mold closure, and the temperature within the mold cavity is measured often, typically every ten seconds. The temperature is fed to a computer . . . ." App. to Pet. for Cert. 38a.
In the portion of the application entitled "Background of the Invention," the following statement is found:149
"By accurate and constant calculation and recalculation of the correct mold time under the temperatures actually present in the mold, the material can be cured accurately and can be relied upon to produce very few rejections, perhaps completely eliminating all rejections due to faulty mold cure." Id., at 41a.
And, in the "Summary of the Invention," this statement appears:151
"A surveillance system is maintained over the mold to determine the actual mold temperature substantially continuously, for example, every ten seconds, and to feed that information to the computer along with the pertinent stored data and along with the elapsed time information." Ibid.
Finally, in a description of a simple hypothetical application using the invention described in Claim 1, this is the reference to the temperature-reading device:153
"Thermocouples, or other temperature-detecting devices, located directly within the mold cavity may read the temperature at the surface where the molding compound touches the mold, so that it actually gets the temperature of the material at that surface." Id., at 45a.
 Id., at 24a.155
 These elements of the rubber-curing process apparently have been well known for years. The following description of the vulcanization process appears in a text published in 1961:156
"Vulcanisation is too important an operation to be left to human control, however experienced and conscientious. Instrumentation makes controlled cure possible, and in consequence instrument engineering is a highly important function in the modern rubber factory, skilled attention being necessary, not only in the maintenance of the instruments but also in their siting. There are instruments available which will indicate, record or control all the services involved in vulcanisation, including time, temperature and pressure, and are capable of setting in motion such operations as the opening and closing of moulds and, in general, will control any process variable which is capable of being converted into an electric charge or pneumatic or hydraulic pressure impulse." Mernagh, supra n. 25, at 1091-1092.
 Commentators critical of the Flook decision have noted the essential similarity of the two inventions:158
"The Diehr invention improved the control system by continually remeasuring the temperature and recalculating the proper cure time. The computer would simultaneously keep track of the elapsed time. When the elapsed time equalled the proper cure time, the rubber would be released automatically from the mold.
"The facts are difficult to distinguish from those in Flook. Both processes involved (1) an initial calculation, (2) continual remeasurement and recalculation, and (3) some control use of the value obtained from the calculation." Novick & Wallenstein, supra n. 5, at 326 (footnotes omitted).
 Indeed, the most significant distinction between the invention at issue in Flook and that at issue in this case lies not in the characteristics of the inventions themselves, but rather in the drafting of the claims. After noting that "[t]he Diehr claims are reminiscent of the claims in Flook," Blumenthal & Riter, supra n. 15, at 502-503 (footnote omitted), the authors of a recent article on the subject observe that the Court of Customs and Patent Appeals' analysis in this case "lends itself to an interesting exercise in claim drafting." Id., at 505. To illustrate their point, the authors redrafted the Diehr and Lutton claims into the format employed in the Flook application:160
"An improved method of calculating the cure time of a rubber molding process utilizing a digital computer comprising the steps of:
"a. inputting into said computer input values including
"1. natural logarithm conversion data (n),
"2. an activation energy constant (C) unique to each batch of rubber being molded,
"3. a constant (X) dependent upon the geometry of the particular mold of the press, and
"4. continuous temperature values (Z) of the mold during molding;
"b. operating said computer for
"1. counting the elapsed cure time,
"2. calculating the cure time from the input values using the Arrhenius equation [l]n V=CZ+X, where V is the total cure time, and
"c. providing output signals from said computer when said calculated cure time is equal to said elapsed cure time." Ibid.
The authors correctly conclude that even the lower court probably would have found that this claim was drawn to unpatentable subject matter under § 101. Id., at 505-506.162
 In addition to confusing the requirements of §§ 101 and 102, the Court also misapprehends the record in this case when it suggests that the Diehr and Lutton patent application may later be challenged for failure to satisfy the requirements of §§ 102 and 103. See ante, at 191. This suggestion disregards the fact that the applicants overcame all objections to issuance of the patent except the objection predicated on § 101. The Court seems to assume that §§ 102 and 103 issues of novelty and obviousness remain open on remand. As I understand the record, however, those issues have already been resolved. See Brief for Respondents 11-14; Reply Memorandum for Petitioner 3-4, and n. 4. Therefore, the Court is now deciding that the patent will issue.163
 The early cases that the Court of Customs and Patent Appeals refused to follow in Prater, Musgrave, and Benson had recognized the distinction between the § 101 requirement that what the applicant claims to have invented must be patentable subject matter and the § 102 requirement that the invention must actually be novel. See, e. g., In re Shao Wen Yuan, 38 C. C. P. A. (Pat.), at 973-976, 188 F. 2d, at 382-383; In re Abrams, 38 C. C. P. A. (Pat.), at 951-952, 188 F. 2d, at 169; In re Heritage, 32 C. C. P. A. (Pat.), at 1173-1174, 1176-1177, 150 F. 2d, at 556, 558; Halliburton Oil Well Cementing Co. v. Walker, 146 F. 2d, at 821, 823. The lower court's error in this case, and its unenthusiastic reception of Gottschalk v. Benson and Parker v. Flook, is, of course, consistent with its expansive reading of § 101 in Tarczy-Hornoch, Prater, and their progeny.164
 The Court's opinion in Flook itself pointed out this distinction:165
"The obligation to determine what type of discovery is sought to be patented must precede the determination of whether that discovery is, in fact, new or obvious." 437 U. S., at 593.
As the Court of Customs and Patent Appeals noted in this case, "for the claim to be statutory, there must be some substance to it other than the recitation and solution of the equation or formula." 602 F. 2d, at 988. See Comment, 62 J. Pat. Off. Soc., supra n. 22, at 522-523.167
 The Court fails to focus upon what Diehr and Lutton claim to have discovered apparently because it believes that this method of analysis would improperly import novelty considerations into § 101. See ante, at 188-191, 193, n. 15. Rather than directing its attention to the applicants' claimed discovery, the Court instead focuses upon the general industrial context in which the applicants intend their discovery to be used. Implicit in this interpretation of the patent application is the assumption that, as long as the claims describe a specific implication of the applicants' discovery, patentable subject matter is defined. This assumption was expressly rejected in Flook:168
"This assumption is based on respondent's narrow reading of Benson, and is as untenable in the context of § 101 as it is in the context of that case. It would make the determination of patentable subject matter depend simply on the draftsman's art and would ill serve the principles underlying the prohibition against patents for `ideas' or phenomena of nature. The rule that the discovery of a law of nature cannot be patented rests, not on the notion that natural phenomena are not processes, but rather on the more fundamental understanding that they are not the kind of `discoveries' that the statute was enacted to protect." 437 U. S., at 593 (footnote omitted).
 A few excerpts from the original patent application will emphasize this point:170
"The invention will probably best be understood by first describing a simple example, in which a single mold is involved and in which the information is relatively static.
"A standard digital computer may be employed in this method. It has a data storage bank of suitable size which, of course, may vary when many molds are used and when more refinements are employed. However, Fig. 1 shows a relatively simple case which achieves results that are vast improvements over what has been done up to now. . . .
"The data bank of the computer is provided with a digital input into which the time-temperature cure data for the compound involved is fed, as shown in Fig. 1. All the data is available to the computer upon call, by random access, and the call can be automatic depending upon the temperature actually involved. In other words, the computer over and over questions the data storage, asking, what is the proper time of cure for the following summation of temperatures? The question may be asked each second, and the answer is readily provided.
"Recalculation continues until the time that has elapsed since mold closure corresponds with the calculated time. Then, the computer actuates the mold-opening device and the mold is automatically opened." App. to Pet. for Cert. 43a-45a.
The Figure 1 referred to in the application is as follows:172
Id., at 53a.174
 In Benson, we explained the term "algorithm" in the following paragraph:175
"The patent sought is on a method of programming a general-purpose digital computer to convert signals from binary-coded decimal form into pure binary form. A procedure for solving a given type of mathematical problem is known as an `algorithm.' The procedures set forth in the present claims are of that kind; that is to say, they are a generalized formulation for programs to solve mathematical problems of converting one form of numerical representation to another. From the generic formulation, programs may be developed as specific applications." 409 U. S., at 65.
 In Flook, the Court's analysis of the postsolution activity recited in the patent application turned, not on the relative significance of that activity in the catalytic conversion process, but rather on the fact that that activity was not a part of the applicant's discovery:177
"The notion that post-solution activity, no matter how conventional or obvious in itself, can transform an unpatentable principle into a patentable process exalts form over substance. A competent draftsman could attach some form of post-solution activity to almost any mathematical formula; the Pythagorean theorem would not have been patentable, or partially patentable, because a patent application contained a final step indicating that the formula, when solved, could be usefully applied to existing surveying techniques. The concept of patentable subject matter under § 101 is not `like a nose of wax which may be turned and twisted in any direction . . . .' White v. Dunbar, 119 U. S. 47, 51." 437 U. S., at 590 (footnote omitted).
 Although the Court of Customs and Patent Appeals erred because it ignored the distinction between the § 101 requirement that the applicant must claim to have discovered a novel process and the § 102 requirement that the discovery must actually be novel, that court correctly rejected the argument that any difference between Claim 11 and the earlier claims was relevant to the § 101 inquiry. See 602 F. 2d, at 984, 987-988.179
 This well-established precedent was reviewed in Parker v. Flook:180
"Mackay Radio and Funk Bros. point to the proper analysis for this case: The process itself, not merely the mathematical algorithm, must be new and useful. Indeed, the novelty of the mathematical algorithm is not a determining factor at all. Whether the algorithm was in fact known or unknown at the time of the claimed invention, as one of the `basic tools of scientific and technological work,' see Gottschalk v. Benson, 409 U. S., at 67, it is treated as though it were a familiar part of the prior art." 437 U. S., at 591-592.
 For example, the Association of Data Processing Service Organizations, appearing as amicus curiae in Flook, made the following policy argument:182
"The need of the incentive of patents for software is at least as great as that of the incentive available for hardware, because: "Today, providing computer software involves greater . . . risk than providing computer. . . hardware. . . .'
"To a financial giant, the economic value of a patent may not loom large; to the small software products companies upon which the future of the development of quality software depends, the value of the patent in financing a small company may spell the difference between life and death. To banks and financial institutions the existence of a patent or even the potentiality of obtaining one may well be a decisive factor in determining whether a loan should be granted. To prospective investors a patent or the possibility of obtaining one may be the principal element in the decision whether to invest.
"Making clear that patents may be available for inventions in software would unleash important innovative talent. It would have the direct opposite effect forecast by the . . . hardware manufacturers; it would enable competition with those companies and provide the needed incentive to stimulate innovation." Brief for ADAPSO as Amicus Curiae in Parker v. Flook, O. T. 1977, No. 77-642, p. 44 (footnote omitted).
 Gemignani, supra n. 1, at 309. In a footnote to that comment, Professor Gemignani added that the rate of growth of the software industry "has been even faster lately than that of the hardware industry which does enjoy patent protections." Id., at 309, n. 259. Other commentators are in accord. See Nycum, Legal Protection for Computer Programs, 1 Computer L. J. 1, 55-58 (1978); Note, Protection of Computer Programs: Resurrection of the Standard, 50 Notre Dame Law. 333, 344 (1974).184
 See, e. g., Gemignani, supra n. 1, at 301-312; Keefe & Mahn, Protecting Software: Is It Worth All the Trouble?, 62 A. B. A. J. 906, 907 (1976).185
 This concern influenced the President's Commission on the Patent System when it recommended against patent protection for computer programs. In its report, the President's Commission stated:186
"The Patent Office now cannot examine applications for programs because of the lack of a classification technique and the requisite search files. Even if these were available, reliable searches would not be feasible or economic because of the tremendous volume of prior art being generated. Without this search, the patenting of programs would be tantamount to mere registration and the presumption of validity would be all but nonexistent." Report of the President's Commission, supra n. 10, at 13.
 It is noteworthy that the position of the Court of Customs and Patent Appeals in the process patent area had been consistent with that of the Commissioner of Patents and Trademarks for decades prior to 1968. As discussed in Part I, supra, in that year the court rejected two longstanding doctrines that would have foreclosed patentability for most computer programs under § 101.188
 A number of authorities have drawn the conclusion that the terms are in fact synonymous. See, e. g., Novick & Wallenstein, supra n. 5, at 333, n. 172; Anderson, Algorithm, 1 Encyclopedia of Computer Science & Technology 364, 369 (J. Belzer, A. Holzman & A. Kent eds. 1975); E. Horowitz & S. Sahni, Fundamentals of Computer Algorithms 2 (1978); A. Tanenbaum, Structured Computer Organization 10 (1976). Cf. Blumenthal & Riter, supra n. 15, at 455-456; Gemignani, supra n. 1, at 271-273, 276, n. 37.
APPEAL from the Circuit Court of the United States for the Southern District of Ohio.17
The facts are stated in the opinion of the court.19
Mr. Alphonso Taft and Mr. H. P. Lloyd for the appellant.21
Mr. C. W. Moulton and Mr. M. I. Southard for the appellee.23
MR. JUSTICE BRADLEY delivered the opinion of the court.25
Charles Selden, the testator of the complainant in this case, in the year 1859 took the requisite steps for obtaining the copyright27
of a book, entitled 'Selden's Condensed Ledger, or Book-keeping Simplified,' the object of which was to exhibit and explain a peculiar system of book-keeping. In 1860 and 1861, he took the copyright of several other books, containing additions to and improvements upon the said system. The bill of complaint was filed against the defendant, Baker, for an alleged infringement of these copyrights. The latter, in his answer, denied that Selden was the author or designer of the books, and denied the infringement charged, and contends on the argument that the matter alleged to be infringed is not a lawful subject of copyright.31
The parties went into proofs, and the various books of the complainant, as well as those sold and used by the defendant, were exhibited before the examiner, and witnesses were examined to both sides. A decree was rendered for the complainant, and the defendant appealed.33
The book or series of books of which the complainant claims the copyright consists of an introductory essay explaining the system of book-keeping referred to, to which are annexed certain forms or banks, consisting of ruled lines, and headings, illustrating the system and showing how it is to be used and carried out in practice. This system effects the same results as book-keeping by double entry; but, by a peculiar arrangement of columns and headings, presents the entire operation, of a day, a week, or a month, on a single page, or on two pages facing each other, in an account-book. The defendant uses a similar plan so far as results are concerned; but makes a different arrangement of the columns, and uses different headings. If the complainant's testator had the exclusive right to the use of the system explained in his book, it would be difficult to contend that the defendant does not infringe it, notwithstanding the difference in his form of arrangement; but if it be assumed that the system is open to public use, it seems to be equally difficult to contend that the books made and sold by the defendant are a violation of the copyright of the complainant's book considered merely as a book explanatory of the system. Where the truths of a science or the methods of an art are the common property of the whole world, any author has the right to express the one, or explain and use the other, in35
his own way. As an author, Selden explained the system in a particular way. It may be conceded that Baker makes and uses account-books arranged on substantially the same system; but the proof fails to show that he has violated the copyright of Selden's book, regarding the latter merely as an explanatory work; or that he has infringed Selden's right in any way, unless the latter became entitled to an exclusive right in the system.39
The evidence of the complainant is principally directed to the object of showing that Baker uses the same system as that which is explained and illustrated in Selden's books. It becomes important, therefore, to determine whether, in obtaining the copyright of his books, he secured the exclusive right to the use of the system or method of book-keeping which the said books are intended to illustrate and explain. It is contended that he has secured such exclusive right, because no one can use the system without using substantially the same ruled lines and headings which he was appended to his books in illustration of it. In other words, it is contended that the ruled lines and headings, given to illustrate the system, are a part of the book, and, as such, are secured by the copyright; and that no one can make or use similar ruled lines and headings, or ruled lines and headings made and arranged on substantially the same system, without violating the copyright. And this is really the question to be decided in this case. Stated in another form, the question is, whether the exclusive property in a system of book-keeping can be claimed, under the law or copyright, by means of a book in which that system is explained? The complainant's bill, and the case made under it, are based on the hypothesis that it can be.41
It cannot be pretended, and indeed it is not seriously urged, that the ruled lines of the complainant's account-book can be claimed under any special class of objects, other than books, named in the law of copyright existing in 1859. The law then in force was that of 1831, and specified only books, maps, charts, musical compositions, prints, and engravings. An account-book, consisting of ruled lines and blank columns, cannot be called by any of these names unless by that of a book.43
There is no doubt that a work on the subject of book-keeping,45
though only explanatory of well-known systems, may be the subject of a copyright; but, then, it is claimed only as a book. Such a book may be explanatory either of old systems, or of an entirely new system; and, considered as a book, as the work of an author, conveying information on the subject of book-keeping, and containing detailed explanations of the art, it may be a very valuable acquisition to the practical knowledge of the community. But there is a clear distinction between the book, as such, and the art which it is intended to illustrate. The mere statement of the proposition is so evident, that it requires hardly any argument to support it. The same distinction may be predicated of every other art as well as that of book-keeping. A treatise on the composition and use of medicines, be they old or new; on the construction and use of ploughs, or watches, or churns; or on the mixture and application of colors for painting or dyeing; or on the mode of drawing lines to produce the effect of perspective, would be the subject of copyright; but no one would contend that the copyright of the treatise would give the exclusive right to the art or manufacture described therein. The copyright of the book, if not pirated from other works, would be valid without regard to the novelty, or want of novelty, of its subject-matter. The novelty of the art or thing described or explained has nothing to do with the validity of the copyright. To give to the author of the book an exclusive property in the art described therein, when no examination of its novelty has ever been officially made, would be a surprise and a fraud upon the public. That is the province of letters-patent, not of copyright. The claim to an invention or discovery of an art or manufacture must be subjected to the examination of the Patent Office before an exclusive right therein can be obtained; and it can only be secured by a patent from the government.49
The difference between the two things, letters-patent and copyright, may be illustrated by reference to the subjects just enumerated. Take the case of medicines. Certain mixtures are found to be of great value in the healing art. If the discoverer writes and publishes a book on the subject (as regular physicians generally do), he gains no exclusive right to the manufacture and sale of the medicine; he gives that to the51
public. If he desires to acquire such exclusive right, he must obtain a patent for the mixture as a new art, manufacture, or composition of matter. He may copyright his book, if he pleases; but that only secures to him the exclusive right of printing and publishing his book. So of all other inventions or discoveries.55
The copyright of a book on perspective, no matter how many drawings and illustrations it may contain, gives no exclusive right to the modes of drawing described, though they may never have been known or used before. By publishing the book, without getting a patent for the art, the latter is given to the public. The fact that the art described in the book by illustrations of lines and figures which are reproduced in practice in the application of the art, makes no difference. Those illustrations are the mere language employed by the author to convey his ideas more clearly. Had he used words of description instead of diagrams (which merely stand in the place of words), there could not be the slightest doubt that others, applying the art to practical use, might lawfully draw the lines and diagrams which were in the author's mind, and which he thus described by words in his book.57
The copyright of a work on mathematical science cannot give to the author an exclusive right to the methods of operation which he propounds, or to the diagrams which he employs to explain them, so as to prevent an engineer from using them whenever occasion requires. The very object of publishing a book on science or the useful arts is to communicate to the world the useful knowledge which it contains. But this object would be frustrated if the knowledge could not be used without incurring the guilt of piracy of the book. And where the art it teaches cannot be used without employing the methods and diagrams used to illustrate the book, or such as are similar to them, such methods and diagrams are to be considered as necessary incidents to the art, and given therewith to the public; not given for the purpose of publication in other works explanatory of the art, but for the purpose of practical application.59
Of course, these observations are not intended to apply to ornamental designs, or pictorial illustrations addressed to the taste. Of these it may be said, that their form is their essence,61
and their object, the production of pleasure in their contemplation. This is their final end. They are as much the product of genius and the result of composition, as are the lines of the poet or the historian's period. On the other hand, the teachings of science and the rules and methods of useful art have their final end in application and use; and this application and use are what the public derive from the publication of a book which teaches them. But as embodied and taught in a literary composition or book, their essence consists only in their statement. This alone is what is secured by the copyright. The use by another of the same methods of statement, whether in words or illustrations, in a book published for teaching the art, would undoubtedly be an infringement of the copyright.65
Recurring to the case before us, we observe that Charles Selden, by his books, explained and described a peculiar system of book-keeping, and illustrated his method by means of ruled lines and blank columns, with proper headings on a page, or on successive pages. Now, whilst no one has a right to print or publish his book, or any material part thereof, as a book intended to convey instruction in the art, any person may practise and use the art itself which he has described and illustrated therein. The use of the art is a totally different thing from a publication of the book explaining it. The copyright of a book on book-keeping cannot secure the exclusive right to make, sell, and use account-books prepared upon the plan set forth in such book. Whether the art might or might not have been patented, is a question which is not before us. It was not patented, and is open and free to the use of the public. And, of course, in using the art, the ruled lines and headings of accounts must necessarily be used as incident to it.67
The plausibility of the claim put forward by the complainant in this case arises from a confusion of ideas produced by the peculiar nature of the art described in the books which have been made the subject of copyright. In describing the art, the illustrations and diagrams employed happen to correspond more closely than usual with the actual work performed by the operator who uses the art. Those illustrations and diagrams consist of ruled lines and headings of accounts; and69
it is similar ruled lines and headings of accounts which, in the application of the art, the book-keeper makes with his pen, or the stationer with his press; whilst in most other cases the diagrams and illustrations can only be represented in concrete forms of wood, metal, stone, or some other physical embodiment. But the principle is the same in all. The description of the art in a book, though entitled to the benefit of copyright, lays no foundation for an exclusive claim to the art itself. The object of the one is explanation; the object of the other is use. The former may be secured by copyright. The latter can only be secured, if it can be secured at all, by letters-patent.73
The remarks of Mr. Justice Thompson in the Circuit Court in Clayton v. Stone & Hall (2 Paine, 392), in which copyright was claimed in a daily price-current, are apposite and instructive. He says: 'In determining the true construction to be given to the act of Congress, it is proper to look at the Constitution of the United States, to aid us in ascertaining the nature of the property intended to be protected. 'Congress shall have power to promote the progress of science and useful arts, by securing for limited times to authors and inventors the exclusive right to their writings and discoveries.' The act in question was passed in execution of the power here given, and the object, therefore, was the promotion of science; and it would certainly be a pretty extraordinary view of the sciences to consider a daily or weekly publication of the state of the market as falling within any class of them. They are of a more fixed, permanent, and durable character. The term 'science' cannot, with any propriety, by applied to a work of so fluctuating and fugitive a form as that of a newspaper or price-current, the subject-matter of which is daily changing, and is of mere temporary use. Although great praise may be due to the plaintiffs for their industry and enterprise in publishing this paper, yet the law does not contemplate their being rewarded in this way: it must seek patronage and protection from its utility to the public, and not a work of science. The title of the act of Congress is, 'for the encouragement of learning,' and was not intended for the encouragement of mere industry, unconnected with learning and the sciences. . . . We are, accordingly, of opinion that the paper in question is not75
a book the copyright to which can be secured under the act of Congress.'79
The case of Cobbett v. Woodward (Law Rep. 14 Eq. 407) was a claim to copyright in a catalogue of furniture which the publisher had on sale in his establishment, illustrated with many drawings of furniture and decorations. The defendants, being dealers in the same business, published a similar book, and copied many of the plaintiff's drawings, though it was shown that they had for sale the articles represented thereby.81
The court held that these drawings were not subjects of copyright. Lord Romilly, M. R., said: 'This is a mere advertisement for the sale of particular articles which any one might imitate, and any one might advertise for sale. If a man not being a vendor of any of the articles in question were to publish a work for the purpose of informing the public of what was the most convenient species of articles for household furniture, or the most graceful species of decorations for articles of home furniture, what they ought to cost, and where they might be bought, and were to illustrate his work with designs of each article he described,—such a work as this could not be pirated with impunity, and the attempt to do so would be stopped by the injunction of the Court of Chancery; yet if it were done with no such object, but solely for the purpose of advertising particular articles for sale, and promoting the private trade of the publisher by the sale of articles which any other person might sell as well as the first advertiser, and if in fact it contained little more than an illustrated inventory of the contents of a warehouse, I know of no law which, while it would not prevent the second advertiser from selling the same articles, would prevent him from using the same advertisement; provided he did not in such advertisement by any device suggest that he was selling the works and designs of the first advertiser.'83
Another case, that of Page v. Wisden (20 L. T. N. S. 435), which came before Vice-Chancellor Malins in 1869, has some resemblance to the present. There a copyright was claimed in a cricket scoring-shett, and the Vice-Chancellor held that it was not a fit subject for copyright, partly because it was not new, but also because 'to say that a particular85
mode of ruling a book constituted an object for a copyright is absurd.'89
These cases, if not precisely in point, come near to the matter in hand, and, in our view, corroborate the general proposition which we have laid down.91
In Drury v. Ewing (1 Bond, 540), which is much relied on by the complainant, a copyright was claimed in a chart of patterns for cutting dresses and basques for ladies, and coats, jackets, &c., for boys. It is obvious that such designs could only be printed and published for information, and not for use in themselves. Their practical use could only be exemplified in cloth on the tailor's board and under his shears; in other words, by the application of a mechanical operation to the cutting of cloth in certain patterns and forms. Surely the exclusive right to this practical use was not reserved to the publisher by his copyright of the chart. Without undertaking to say whether we should or should not concur in the decision in that case, we think it cannot control the present.93
The conclusion to which we have come is, that blank account-books are not the subject of copyright; and that the mere copyright of Selden's book did not confer upon him the exclusive right to make and use account-books, ruled and arranged as designated by him and described and illustrated in said book.95
The decree of the Circuit Court must be reversed, and the cause remanded with instructions to dismiss the complainant's bill; and it is97
Supreme Court of the United States
Argued January 9, 1991
Decided March 27, 1991
Kyler Knobbe argued the cause and filed briefs for petitioner.6
James M. Caplinger, Jr., argued the cause and filed a brief for respondent.[*]7
JUSTICE O'CONNOR delivered the opinion of the Court.8
This case requires us to clarify the extent of copyright protection available to telephone directory white pages.10
Rural Telephone Service Company, Inc., is a certified public utility that provides telephone service to several communities in northwest Kansas. It is subject to a state regulation that requires all telephone companies operating in Kansas to issue annually an updated telephone directory. Accordingly, as a condition of its monopoly franchise, Rural publishes a typical telephone directory, consisting of white pages and yellow pages. The white pages list in alphabetical order the names of Rural's subscribers, together with their towns and telephone numbers. The yellow pages list Rural's business subscribers alphabetically by category and feature classified advertisements of various sizes. Rural distributes its directory free of charge to its subscribers, but earns revenue by selling yellow pages advertisements.12
Feist Publications, Inc., is a publishing company that specializes in area-wide telephone directories. Unlike a typical directory, which covers only a particular calling area, Feist's area-wide directories cover a much larger geographical range, reducing the need to call directory assistance or consult multiple directories. The Feist directory that is the subject of this litigation covers 11 different telephone service areas in 15 counties and contains 46,878 white pages listings—compared to Rural's approximately 7,700 listings. Like Rural's directory, Feist's is distributed free of charge and includes both white pages and yellow pages. Feist and Rural compete vigorously for yellow pages advertising.13
As the sole provider of telephone service in its service area, Rural obtains subscriber information quite easily. Persons desiring telephone service must apply to Rural and provide their names and addresses; Rural then assigns them a telephone number. Feist is not a telephone company, let alone one with monopoly status, and therefore lacks independent access to any subscriber information. To obtain white pages listings for its area-wide directory, Feist approached each of the 11 telephone companies operating in northwest Kansas and offered to pay for the right to use its white pages listings.14
Of the 11 telephone companies, only Rural refused to license its listings to Feist. Rural's refusal created a problem for Feist, as omitting these listings would have left a gaping hole in its area-wide directory, rendering it less attractive to potential yellow pages advertisers. In a decision subsequent to that which we review here, the District Court determined that this was precisely the reason Rural refused to license its listings. The refusal was motivated by an unlawful purpose "to extend its monopoly in telephone service to a monopoly in yellow pages advertising." Rural Telephone Service Co. v. Feist Publications, Inc., 737 F. Supp. 610, 622 (Kan. 1990).15
Unable to license Rural's white pages listings, Feist used them without Rural's consent. Feist began by removing several thousand listings that fell outside the geographic range of its area-wide directory, then hired personnel to investigate the 4,935 that remained. These employees verified the data reported by Rural and sought to obtain additional information. As a result, a typical Feist listing includes the individual's street address; most of Rural's listings do not. Notwithstanding these additions, however, 1,309 of the 46,878 listings in Feist's 1983 directory were identical to listings in Rural's 1982-1983 white pages. App. 54 (¶ 15-16), 57. Four of these were fictitious listings that Rural had inserted into its directory to detect copying.16
Rural sued for copyright infringement in the District Court for the District of Kansas taking the position that Feist, in compiling its own directory, could not use the information contained in Rural's white pages. Rural asserted that Feist's employees were obliged to travel door-to-door or conduct a telephone survey to discover the same information for themselves. Feist responded that such efforts were economically impractical and, in any event, unnecessary because the information copied was beyond the scope of copyright protection. The District Court granted summary judgment to Rural, explaining that "[c]ourts have consistently held that telephone directories are copyrightable" and citing a string of lower court decisions. 663 F. Supp. 214, 218 (1987). In an unpublished opinion, the Court of Appeals for the Tenth Circuit affirmed "for substantially the reasons given by the district court." App. to Pet. for Cert. 4a, judgt. order reported at 916 F. 2d 718 (1990). We granted certiorari, 498 U. S. 808 (1990), to determine whether the copyright in Rural's directory protects the names, towns, and telephone numbers copied by Feist.18
This case concerns the interaction of two well-established propositions. The first is that facts are not copyrightable; the other, that compilations of facts generally are. Each of these propositions possesses an impeccable pedigree. That there can be no valid copyright in facts is universally understood. The most fundamental axiom of copyright law is that "[n]o author may copyright his ideas or the facts he narrates." Harper & Row, Publishers, Inc. v. Nation Enterprises, 471 U. S. 539, 556 (1985). Rural wisely concedes this point, noting in its brief that "[f]acts and discoveries, of course, are not themselves subject to copyright protection." Brief for Respondent 24. At the same time, however, it is beyond dispute that compilations of facts are within the subject matter of copyright. Compilations were expressly mentioned in the Copyright Act of 1909, and again in the Copyright Act of 1976.22
There is an undeniable tension between these two propositions. Many compilations consist of nothing but raw data— i. e., wholly factual information not accompanied by any original written expression. On what basis may one claim a copyright in such a work? Common sense tells us that 100 uncopyrightable facts do not magically change their status when gathered together in one place. Yet copyright law seems to contemplate that compilations that consist exclusively of facts are potentially within its scope.23
The key to resolving the tension lies in understanding why facts are not copyrightable. The sine qua non of copyright is originality. To qualify for copyright protection, a work must be original to the author. See Harper & Row, supra, at 547-549. Original, as the term is used in copyright, means only that the work was independently created by the author (as opposed to copied from other works), and that it possesses at least some minimal degree of creativity. 1 M. Nimmer & D. Nimmer, Copyright §§ 2.01[A], [B] (1990) (hereinafter Nimmer). To be sure, the requisite level of creativity is extremely low; even a slight amount will suffice. The vast majority of works make the grade quite easily, as they possess some creative spark, "no matter how crude, humble or obvious" it might be. Id., § 1.08[C]. Originality does not signify novelty; a work may be original even though it closely resembles other works so long as the similarity is fortuitous, not the result of copying. To illustrate, assume that two poets, each ignorant of the other, compose identical poems. Neither work is novel, yet both are original and, hence, copyrightable. See Sheldon v. Metro-Goldwyn Pictures Corp., 81 F. 2d 49, 54 (CA2 1936).24
Originality is a constitutional requirement. The source of Congress' power to enact copyright laws is Article I, § 8, cl. 8, of the Constitution, which authorizes Congress to "secur[e] for limited Times to Authors . . . the exclusive Right to their respective Writings." In two decisions from the late 19th century—The Trade-Mark Cases, 100 U. S. 82 (1879); and Burrow-Giles Lithographic Co. v. Sarony, 111 U. S. 53 (1884)—this Court defined the crucial terms "authors" and "writings." In so doing, the Court made it unmistakably clear that these terms presuppose a degree of originality.25
In The Trade-Mark Cases, the Court addressed the constitutional scope of "writings." For a particular work to be classified "under the head of writings of authors," the Court determined, "originality is required." 100 U. S., at 94. The Court explained that originality requires independent creation plus a modicum of creativity: "[W]hile the word writings may be liberally construed, as it has been, to include original designs for engraving, prints, &c., it is only such as are original, and are founded in the creative powers of the mind. The writings which are to be protected are the fruits of intellectual labor, embodied in the form of books, prints, engravings, and the like." Ibid. (emphasis in original).26
In Burrow-Giles, the Court distilled the same requirement from the Constitution's use of the word "authors." The Court defined "author," in a constitutional sense, to mean "he to whom anything owes its origin; originator; maker." 111 U. S., at 58 (internal quotation marks omitted). As in The Trade-Mark Cases, the Court emphasized the creative component of originality. It described copyright as being limited to "original intellectual conceptions of the author," 111 U. S., at 58, and stressed the importance of requiring an author who accuses another of infringement to prove "the existence of those facts of originality, of intellectual production, of thought, and conception." Id., at 59-60.27
The originality requirement articulated in The Trade-Mark Cases and Burrow-Giles remains the touchstone of copyright protection today. See Goldstein v. California, 412 U. S. 546, 561-562 (1973). It is the very "premise of copyright law." Miller v. Universal City Studios, Inc., 650 F. 2d 1365, 1368 (CA5 1981). Leading scholars agree on this point. As one pair of commentators succinctly puts it: "The originality requirement is constitutionally mandated for all works." Patterson & Joyce, Monopolizing the Law: The Scope of Copyright Protection for Law Reports and Statutory Compilations, 36 UCLA L. Rev. 719, 763, n. 155 (1989) (emphasis in original) (hereinafter Patterson & Joyce). Accord, id., at 759-760, and n. 140; Nimmer § 1.06[A] ("[O]riginality is a statutory as well as a constitutional requirement"); id., § 1.08[C] ("[A] modicum of intellectual labor . . . clearly constitutes an essential constitutional element").28
It is this bedrock principle of copyright that mandates the law's seemingly disparate treatment of facts and factual compilations. "No one may claim originality as to facts." Id., § 2.11[A], p. 2-157. This is because facts do not owe their origin to an act of authorship. The distinction is one between creation and discovery: The first person to find and report a particular fact has not created the fact; he or she has merely discovered its existence. To borrow from Burrow-Giles, one who discovers a fact is not its "maker" or "originator." 111 U. S., at 58. "The discoverer merely finds and records." Nimmer § 2.03[E]. Census takers, for example, do not "create" the population figures that emerge from their efforts; in a sense, they copy these figures from the world around them. Denicola, Copyright in Collections of Facts: A Theory for the Protection of Nonfiction Literary Works, 81 Colum. L. Rev. 516, 525 (1981) (hereinafter Denicola). Census data therefore do not trigger copyright because these data are not "original" in the constitutional sense. Nimmer § 2.03[E]. The same is true of all facts—scientific, historical, biographical, and news of the day. "[T]hey may not be copyrighted and are part of the public domain available to every person." Miller, supra, at 1369.29
Factual compilations, on the other hand, may possess the requisite originality. The compilation author typically chooses which facts to include, in what order to place them, and how to arrange the collected data so that they may be used effectively by readers. These choices as to selection and arrangement, so long as they are made independently by the compiler and entail a minimal degree of creativity, are sufficiently original that Congress may protect such compilations through the copyright laws. Nimmer §§ 2.11[D], 3.03; Denicola 523, n. 38. Thus, even a directory that contains absolutely no protectible written expression, only facts, meets the constitutional minimum for copyright protection if it features an original selection or arrangement. See Harper & Row, 471 U. S., at 547. Accord, Nimmer § 3.03.30
This protection is subject to an important limitation. The mere fact that a work is copyrighted does not mean that every element of the work may be protected. Originality remains the sine qua non of copyright; accordingly, copyright protection may extend only to those components of a work that are original to the author. Patterson & Joyce 800-802; Ginsburg, Creation and Commercial Value: Copyright Protection of Works of Information, 90 Colum. L. Rev. 1865, 1868, and n. 12 (1990) (hereinafter Ginsburg). Thus, if the compilation author clothes facts with an original collocation of words, he or she may be able to claim a copyright in this written expression. Others may copy the underlying facts from the publication, but not the precise words used to present them. In Harper & Row, for example, we explained that President Ford could not prevent others from copying bare historical facts from his autobiography, see 471 U. S., at 556-557, but that he could prevent others from copying his "subjective descriptions and portraits of public figures." Id., at 563. Where the compilation author adds no written expression but rather lets the facts speak for themselves, the expressive element is more elusive. The only conceivable expression is the manner in which the compiler has selected and arranged the facts. Thus, if the selection and arrangement are original, these elements of the work are eligible for copyright protection. See Patry, Copyright in Compilations of Facts (or Why the "White Pages" Are Not Copyrightable), 12 Com. & Law 37, 64 (Dec. 1990) (hereinafter Patry). No matter how original the format, however, the facts themselves do not become original through association. See Patterson & Joyce 776.31
This inevitably means that the copyright in a factual compilation is thin. Notwithstanding a valid copyright, a subsequent compiler remains free to use the facts contained in another's publication to aid in preparing a competing work, so long as the competing work does not feature the same selection and arrangement. As one commentator explains it: "[N]o matter how much original authorship the work displays, the facts and ideas it exposes are free for the taking . . . . [T]he very same facts and ideas may be divorced from the context imposed by the author, and restated or reshuffled by second comers, even if the author was the first to discover the facts or to propose the ideas." Ginsburg 1868.32
It may seem unfair that much of the fruit of the compiler's labor may be used by others without compensation. As Justice Brennan has correctly observed, however, this is not "some unforeseen byproduct of a statutory scheme." Harper & Row, 471 U. S., at 589 (dissenting opinion). It is, rather, "the essence of copyright," ibid., and a constitutional requirement. The primary objective of copyright is not to reward the labor of authors, but "[t]o promote the Progress of Science and useful Arts." Art. I, § 8, cl. 8. Accord, Twentieth Century Music Corp. v. Aiken, 422 U. S. 151, 156 (1975). To this end, copyright assures authors the right to their original expression, but encourages others to build freely upon the ideas and information conveyed by a work. Harper & Row, supra, at 556-557. This principle, known as the idea/expression or fact/expression dichotomy, applies to all works of authorship. As applied to a factual compilation, assuming the absence of original written expression, only the compiler's selection and arrangement may be protected; the raw facts may be copied at will. This result is neither unfair nor unfortunate. It is the means by which copyright advances the progress of science and art.33
This Court has long recognized that the fact/expression dichotomy limits severely the scope of protection in fact-based works. More than a century ago, the Court observed: "The very object of publishing a book on science or the useful arts is to communicate to the world the useful knowledge which it contains. But this object would be frustrated if the knowledge could not be used without incurring the guilt of piracy of the book." Baker v. Selden, 101 U. S. 99, 103 (1880). We reiterated this point in Harper & Row:34
"[N]o author may copyright facts or ideas. The copyright is limited to those aspects of the work—termed `expression'—that display the stamp of the author's originality.35
"[C]opyright does not prevent subsequent users from copying from a prior author's work those constituent elements that are not original—for example . . . facts, or materials in the public domain—as long as such use does not unfairly appropriate the author's original contributions." 471 U. S., at 547-548 (citation omitted).36
This, then, resolves the doctrinal tension: Copyright treats facts and factual compilations in a wholly consistent manner. Facts, whether alone or as part of a compilation, are not original and therefore may not be copyrighted. A factual compilation is eligible for copyright if it features an original selection or arrangement of facts, but the copyright is limited to the particular selection or arrangement. In no event may copyright extend to the facts themselves.38
As we have explained, originality is a constitutionally mandated prerequisite for copyright protection. The Court's decisions announcing this rule predate the Copyright Act of 1909, but ambiguous language in the 1909 Act caused some lower courts temporarily to lose sight of this requirement.40
The 1909 Act embodied the originality requirement, but not as clearly as it might have. See Nimmer § 2.01. The subject matter of copyright was set out in §§ 3 and 4 of the Act. Section 4 stated that copyright was available to "all the writings of an author." 35 Stat. 1076. By using the words "writings" and "author"—the same words used in Article I, § 8, of the Constitution and defined by the Court in The Trade-Mark Cases and Burrow-Giles—the statute necessarily incorporated the originality requirement articulated in the Court's decisions. It did so implicitly, however, thereby leaving room for error.41
Section 3 was similarly ambiguous. It stated that the copyright in a work protected only "the copyrightable component parts of the work." It thus stated an important copyright principle, but failed to identify the specific characteristic—originality—that determined which component parts of a work were copyrightable and which were not.42
Most courts construed the 1909 Act correctly, notwithstanding the less-than-perfect statutory language. They understood from this Court's decisions that there could be no copyright without originality. See Patterson & Joyce 760-761. As explained in the Nimmer treatise: "The 1909 Act neither defined originality, nor even expressly required that a work be `original' in order to command protection. However, the courts uniformly inferred the requirement from the fact that copyright protection may only be claimed by `authors'. . . . It was reasoned that since an author is `the . . . creator, originator' it follows that a work is not the product of an author unless the work is original." Nimmer § 2.01 (footnotes omitted) (citing cases).43
But some courts misunderstood the statute. See, e. g., Leon v. Pacific Telephone & Telegraph Co., 91 F. 2d 484 (CA9 1937); Jeweler's Circular Publishing Co. v. Keystone Publishing Co., 281 F. 83 (CA2 1922). These courts ignored §§ 3 and 4, focusing their attention instead on § 5 of the Act. Section 5, however, was purely technical in nature: It provided that a person seeking to register a work should indicate on the application the type of work, and it listed 14 categories under which the work might fall. One of these categories was "[b]ooks, including composite and cyclopædic works, directories, gazetteers, and other compilations." § 5(a). Section 5 did not purport to say that all compilations were automatically copyrightable. Indeed, it expressly disclaimed any such function, pointing out that "the subject-matter of copyright [i]s defined in section four." Nevertheless, the fact that factual compilations were mentioned specifically in § 5 led some courts to infer erroneously that directories and the like were copyrightable per se, "without any further or precise showing of original—personal—authorship." Ginsburg 1895.44
Making matters worse, these courts developed a new theory to justify the protection of factual compilations. Known alternatively as "sweat of the brow" or "industrious collection," the underlying notion was that copyright was a reward for the hard work that went into compiling facts. The classic formulation of the doctrine appeared in Jeweler's Circular Publishing Co., 281 F., at 88:45
"The right to copyright a book upon which one has expended labor in its preparation does not depend upon whether the materials which he has collected consist or not of matters which are publici juris, or whether such materials show literary skill or originality, either in thought or in language, or anything more than industrious collection. The man who goes through the streets of a town and puts down the names of each of the inhabitants, with their occupations and their street number, acquires material of which he is the author" (emphasis added).46
The "sweat of the brow" doctrine had numerous flaws, the most glaring being that it extended copyright protection in a compilation beyond selection and arrangement—the compiler's original contributions—to the facts themselves. Under the doctrine, the only defense to infringement was independent creation. A subsequent compiler was "not entitled to take one word of information previously published," but rather had to "independently wor[k] out the matter for himself, so as to arrive at the same result from the same common sources of information." Id., at 88-89 (internal quotation marks omitted). "Sweat of the brow" courts thereby eschewed the most fundamental axiom of copyright law—that no one may copyright facts or ideas. See Miller v. Universal City Studios, Inc., 650 F. 2d, at 1372 (criticizing "sweat of the brow" courts because "ensur[ing] that later writers obtain the facts independently . . . is precisely the scope of protection given . . . copyrighted matter, and the law is clear that facts are not entitled to such protection").47
Decisions of this Court applying the 1909 Act make clear that the statute did not permit the "sweat of the brow" approach. The best example is International News Service v. Associated Press, 248 U. S. 215 (1918). In that decision, the Court stated unambiguously that the 1909 Act conferred copyright protection only on those elements of a work that were original to the author. International News Service had conceded taking news reported by Associated Press and publishing it in its own newspapers. Recognizing that § 5 of the Act specifically mentioned "`periodicals, including newspapers,'" § 5(b), the Court acknowledged that news articles were copyrightable. Id., at 234. It flatly rejected, however, the notion that the copyright in an article extended to the factual information it contained: "[T]he news element— the information respecting current events contained in the literary production—is not the creation of the writer, but is a report of matters that ordinarily are publici juris; it is the history of the day." Ibid.[*]48
Without a doubt, the "sweat of the brow" doctrine flouted basic copyright principles. Throughout history, copyright law has "recognize[d] a greater need to disseminate factual works than works of fiction or fantasy." Harper & Row, 471 U. S., at 563. Accord, Gorman, Fact or Fancy: The Implications for Copyright, 29 J. Copyright Soc. 560, 563 (1982). But "sweat of the brow" courts took a contrary view; they handed out proprietary interests in facts and declared that authors are absolutely precluded from saving time and effort by relying upon the facts contained in prior works. In truth, "[i]t is just such wasted effort that the proscription against the copyright of ideas and facts . . . [is] designed to prevent." Rosemont Enterprises, Inc. v. Random House, Inc., 366 F. 2d 303, 310 (CA2 1966), cert. denied, 385 U. S. 1009 (1967). "Protection for the fruits of such research . . . may in certain circumstances be available under a theory of unfair competition. But to accord copyright protection on this basis alone distorts basic copyright principles in that it creates a monopoly in public domain materials without the necessary justification of protecting and encouraging the creation of `writings' by `authors.'" Nimmer § 3.04, p. 3-23 (footnote omitted).50
"Sweat of the brow" decisions did not escape the attention of the Copyright Office. When Congress decided to over-haul the copyright statute and asked the Copyright Office to study existing problems, see Mills Music, Inc. v. Snyder, 469 U. S. 153, 159 (1985), the Copyright Office promptly recommended that Congress clear up the confusion in the lower courts as to the basic standards of copyrightability. The Register of Copyrights explained in his first report to Congress that "originality" was a "basic requisit[e]" of copyright under the 1909 Act, but that "the absence of any reference to [originality] in the statute seems to have led to misconceptions as to what is copyrightable matter." Report of the Register of Copyrights on the General Revision of the U. S. Copyright Law, 87th Cong., 1st Sess., p. 9 (H. Judiciary Comm. Print 1961). The Register suggested making the originality requirement explicit. Ibid.52
Congress took the Register's advice. In enacting the Copyright Act of 1976, Congress dropped the reference to "all the writings of an author" and replaced it with the phrase "original works of authorship." 17 U. S. C. § 102(a). In making explicit the originality requirement, Congress announced that it was merely clarifying existing law: "The two fundamental criteria of copyright protection [are] originality and fixation in tangible form . . . . The phrase `original works of authorship,' which is purposely left undefined, is intended to incorporate without change the standard of originality established by the courts under the present  copyright statute." H. R. Rep. No. 94-1476, p. 51 (1976) (emphasis added) (hereinafter H. R. Rep.); S. Rep. No. 94-473, p. 50 (1975) (emphasis added) (hereinafter S. Rep.). This sentiment was echoed by the Copyright Office: "Our intention here is to maintain the established standards of originality. . . ." Supplementary Report of the Register of Copyrights on the General Revision of U. S. Copyright Law, 89th Cong., 1st Sess., pt. 6, p. 3 (H. Judiciary Comm. Print 1965) (emphasis added).53
To ensure that the mistakes of the "sweat of the brow" courts would not be repeated, Congress took additional measures. For example, § 3 of the 1909 Act had stated that copyright protected only the "copyrightable component parts" of a work, but had not identified originality as the basis for distinguishing those component parts that were copyrightable from those that were not. The 1976 Act deleted this section and replaced it with § 102(b), which identifies specifically those elements of a work for which copyright is not available: "In no case does copyright protection for an original work of authorship extend to any idea, procedure, process, system, method of operation, concept, principle, or discovery, regardless of the form in which it is described, explained, illustrated, or embodied in such work." Section 102(b) is universally understood to prohibit any copyright in facts. Harper & Row, supra, at 547, 556. Accord, Nimmer § 2.03[E] (equating facts with "discoveries"). As with § 102(a), Congress emphasized that § 102(b) did not change the law, but merely clarified it: "Section 102(b) in no way enlarges or contracts the scope of copyright protection under the present law. Its purpose is to restate . . . that the basic dichotomy between expression and idea remains unchanged." H. R. Rep., at 57; S. Rep., at 54.54
Congress took another step to minimize confusion by deleting the specific mention of "directories . . . and other compilations" in § 5 of the 1909 Act. As mentioned, this section had led some courts to conclude that directories were copyrightable per se and that every element of a directory was protected. In its place, Congress enacted two new provisions. First, to make clear that compilations were not copyrightable per se, Congress provided a definition of the term "compilation." Second, to make clear that the copyright in a compilation did not extend to the facts themselves, Congress enacted § 103.55
The definition of "compilation" is found in § 101 of the 1976 Act. It defines a "compilation" in the copyright sense as "a work formed by the collection and assembling of preexisting materials or of data that are selected, coordinated, or arranged in such a way that the resulting work as a whole constitutes an original work of authorship" (emphasis added).56
The purpose of the statutory definition is to emphasize that collections of facts are not copyrightable per se. It conveys this message through its tripartite structure, as emphasized above by the italics. The statute identifies three distinct elements and requires each to be met for a work to qualify as a copyrightable compilation: (1) the collection and assembly of pre-existing material, facts, or data; (2) the selection, coordination, or arrangement of those materials; and (3) the creation, by virtue of the particular selection, coordination, or arrangement, of an "original" work of authorship. "[T]his tripartite conjunctive structure is self-evident, and should be assumed to `accurately express the legislative purpose.'" Patry 51, quoting.57
At first glance, the first requirement does not seem to tell us much. It merely describes what one normally thinks of as a compilation—a collection of pre-existing material, facts, or data. What makes it significant is that it is not the sole requirement. It is not enough for copyright purposes that an author collects and assembles facts. To satisfy the statutory definition, the work must get over two additional hurdles. In this way, the plain language indicates that not every collection of facts receives copyright protection. Otherwise, there would be a period after "data."58
The third requirement is also illuminating. It emphasizes that a compilation, like any other work, is copyrightable only if it satisfies the originality requirement ("an original work of authorship"). Although § 102 states plainly that the originality requirement applies to all works, the point was emphasized with regard to compilations to ensure that courts would not repeat the mistake of the "sweat of the brow" courts by concluding that fact-based works are treated differently and measured by some other standard. As Congress explained it, the goal was to "make plain that the criteria of copyrightable subject matter stated in section 102 apply with full force to works . . . containing preexisting material." H. R. Rep., at 57; S. Rep., at 55.59
The key to the statutory definition is the second requirement. It instructs courts that, in determining whether a fact-based work is an original work of authorship, they should focus on the manner in which the collected facts have been selected, coordinated, and arranged. This is a straightforward application of the originality requirement. Facts are never original, so the compilation author can claim originality, if at all, only in the way the facts are presented. To that end, the statute dictates that the principal focus should be on whether the selection, coordination, and arrangement are sufficiently original to merit protection.60
Not every selection, coordination, or arrangement will pass muster. This is plain from the statute. It states that, to merit protection, the facts must be selected, coordinated, or arranged "in such a way" as to render the work as a whole original. This implies that some "ways" will trigger copyright, but that others will not. See Patry 57, and n. 76. Otherwise, the phrase "in such a way" is meaningless and Congress should have defined "compilation" simply as "a work formed by the collection and assembly of preexisting materials or data that are selected, coordinated, or arranged." That Congress did not do so is dispositive. In accordance with "the established principle that a court should give effect, if possible, to every clause and word of a statute," Moskal v. United States, 498 U. S. 103, 109-110 (1990) (internal quotation marks omitted), we conclude that the statute envisions that there will be some fact-based works in which the selection, coordination, and arrangement are not sufficiently original to trigger copyright protection.61
As discussed earlier, however, the originality requirement is not particularly stringent. A compiler may settle upon a selection or arrangement that others have used; novelty is not required. Originality requires only that the author make the selection or arrangement independently (i. e., without copying that selection or arrangement from another work), and that it display some minimal level of creativity. Presumably, the vast majority of compilations will pass this test, but not all will. There remains a narrow category of works in which the creative spark is utterly lacking or so trivial as to be virtually nonexistent. See generally Bleistein v. Donaldson Lithographing Co., 188 U. S. 239, 251 (1903) (referring to "the narrowest and most obvious limits"). Such works are incapable of sustaining a valid copyright. Nimmer § 2.01[B].62
Even if a work qualifies as a copyrightable compilation, it receives only limited protection. This is the point of § 103 of the Act. Section 103 explains that "[t]he subject matter of copyright . . . includes compilations," § 103(a), but that copyright protects only the author's original contributions—not the facts or information conveyed:63
"The copyright in a compilation . . . extends only to the material contributed by the author of such work, as distinguished from the preexisting material employed in the work, and does not imply any exclusive right in the preexisting material." § 103(b).64
As § 103 makes clear, copyright is not a tool by which a compilation author may keep others from using the facts or data he or she has collected. "The most important point here is one that is commonly misunderstood today: copyright. . . has no effect one way or the other on the copyright or public domain status of the preexisting material." H. R. Rep., at 57; S. Rep., at 55. The 1909 Act did not require, as "sweat of the brow" courts mistakenly assumed, that each subsequent compiler must start from scratch and is precluded from relying on research undertaken by another. See, e. g., Jeweler's Circular Publishing Co., 281 F., at 88-89. Rather, the facts contained in existing works may be freely copied because copyright protects only the elements that owe their origin to the compiler—the selection, coordination, and arrangement of facts.65
In summary, the 1976 revisions to the Copyright Act leave no doubt that originality, not "sweat of the brow," is the touchstone of copyright protection in directories and other fact-based works. Nor is there any doubt that the same was true under the 1909 Act. The 1976 revisions were a direct response to the Copyright Office's concern that many lower courts had misconstrued this basic principle, and Congress emphasized repeatedly that the purpose of the revisions was to clarify, not change, existing law. The revisions explain with painstaking clarity that copyright requires originality, § 102(a); that facts are never original, § 102(b); that the copyright in a compilation does not extend to the facts it contains, § 103(b); and that a compilation is copyrightable only to the extent that it features an original selection, coordination, or arrangement, § 101.66
The 1976 revisions have proven largely successful in steering courts in the right direction. A good example is Miller v. Universal City Studios, Inc., 650 F. 2d, at 1369-1370: "A copyright in a directory . . . is properly viewed as resting on the originality of the selection and arrangement of the factual material, rather than on the industriousness of the efforts to develop the information. Copyright protection does not extend to the facts themselves, and the mere use of information contained in a directory without a substantial copying of the format does not constitute infringement" (citation omitted). Additionally, the Second Circuit, which almost 70 years ago issued the classic formulation of the "sweat of the brow" doctrine in Jeweler's Circular Publishing Co., has now fully repudiated the reasoning of that decision. See, e. g., Financial Information, Inc. v. Moody's Investors Service, Inc., 808 F. 2d 204, 207 (CA2 1986), cert. denied, 484 U. S. 820 (1987); Financial Information, Inc. v. Moody's Investors Service, Inc., 751 F. 2d 501, 510 (CA2 1984) (Newman, J., concurring); Hoehling v. Universal City Studios, Inc., 618 F. 2d 972, 979 (CA2 1980). Even those scholars who believe that "industrious collection" should be rewarded seem to recognize that this is beyond the scope of existing copyright law. See Denicola 516 ("[T]he very vocabulary of copyright is ill suited to analyzing property rights in works of nonfiction"); id., at 520-521, 525; Ginsburg 1867, 1870.68
There is no doubt that Feist took from the white pages of Rural's directory a substantial amount of factual information. At a minimum, Feist copied the names, towns, and telephone numbers of 1,309 of Rural's subscribers. Not all copying, however, is copyright infringement. To establish infringement, two elements must be proven: (1) ownership of a valid copyright, and (2) copying of constituent elements of the work that are original. See Harper & Row, 471 U. S., at 548. The first element is not at issue here; Feist appears to concede that Rural's directory, considered as a whole, is subject to a valid copyright because it contains some foreword text, as well as original material in its yellow pages advertisements. See Brief for Petitioner 18; Pet. for Cert. 9.70
The question is whether Rural has proved the second element. In other words, did Feist, by taking 1,309 names, towns, and telephone numbers from Rural's white pages, copy anything that was "original" to Rural? Certainly, the raw data does not satisfy the originality requirement. Rural may have been the first to discover and report the names, towns, and telephone numbers of its subscribers, but this data does not "ow[e] its origin'" to Rural. Burrow-Giles, 111 U. S., at 58. Rather, these bits of information are uncopyrightable facts; they existed before Rural reported them and would have continued to exist if Rural had never published a telephone directory. The originality requirement "rule[s] out protecting . . . names, addresses, and telephone numbers of which the plaintiff by no stretch of the imagination could be called the author." Patterson & Joyce 776.71
Rural essentially concedes the point by referring to the names, towns, and telephone numbers as "preexisting material." Brief for Respondent 17. Section 103(b) states explicitly that the copyright in a compilation does not extend to "the preexisting material employed in the work."72
The question that remains is whether Rural selected, coordinated, or arranged these uncopyrightable facts in an original way. As mentioned, originality is not a stringent standard; it does not require that facts be presented in an innovative or surprising way. It is equally true, however, that the selection and arrangement of facts cannot be so mechanical or routine as to require no creativity whatsoever. The standard of originality is low, but it does exist. See Patterson & Joyce 760, n. 144 ("While this requirement is sometimes characterized as modest, or a low threshold, it is not without effect") (internal quotation marks omitted; citations omitted). As this Court has explained, the Constitution mandates some minimal degree of creativity, see The Trade-Mark Cases, 100 U. S., at 94; and an author who claims infringement must prove "the existence of . . . intellectual production, of thought, and conception." Burrow-Giles, supra, at 59-60.73
The selection, coordination, and arrangement of Rural's white pages do not satisfy the minimum constitutional standards for copyright protection. As mentioned at the outset, Rural's white pages are entirely typical. Persons desiring' telephone service in Rural's service area fill out an application and Rural issues them a telephone number. In preparing its white pages, Rural simply takes the data provided by its subscribers and lists it alphabetically by surname. The end product is a garden-variety white pages directory, devoid of even the slightest trace of creativity.74
Rural's selection of listings could not be more obvious: It publishes the most basic information—name, town, and telephone number—about each person who applies to it for telephone service. This is "selection" of a sort, but it lacks the modicum of creativity necessary to transform mere selection into copyrightable expression. Rural expended sufficient effort to make the white pages directory useful, but insufficient creativity to make it original.75
We note in passing that the selection featured in Rural's white pages may also fail the originality requirement for another reason. Feist points out that Rural did not truly "select" to publish the names and telephone numbers of its subscribers; rather, it was required to do so by the Kansas Corporation Commission as part of its monopoly franchise. See 737 F. Supp., at 612. Accordingly, one could plausibly conclude that this selection was dictated by state law, not by Rural.76
Nor can Rural claim originality in its coordination and arrangement of facts. The white pages do nothing more than list Rural's subscribers in alphabetical order. This arrangement may, technically speaking, owe its origin to Rural; no one disputes that Rural undertook the task of alphabetizing the names itself. But there is nothing remotely creative about arranging names alphabetically in a white pages directory. It is an age-old practice, firmly rooted in tradition and so commonplace that it has come to be expected as a matter of course. See Brief for Information Industry Association et al. as Amici Curiae 10 (alphabetical arrangement "is universally observed in directories published by local exchange telephone companies"). It is not only unoriginal, it is practically inevitable. This time-honored tradition does not possess the minimal creative spark required by the Copyright Act and the Constitution.77
We conclude that the names, towns, and telephone numbers copied by Feist were not original to Rural and therefore were not protected by the copyright in Rural's combined white and yellow pages directory. As a constitutional matter, copyright protects only those constituent elements of a work that possess more than a de minimis quantum of creativity. Rural's white pages, limited to basic subscriber information and arranged alphabetically, fall short of the mark. As a statutory matter, 17 U. S. C. § 101 does not afford protection from copying to a collection of facts that are selected, coordinated, and arranged in a way that utterly lacks originality. Given that some works must fail, we cannot imagine a more likely candidate. Indeed, were we to hold that Rural's white pages pass muster, it is hard to believe that any collection of facts could fail.78
Because Rural's white pages lack the requisite originality, Feist's use of the listings cannot constitute infringement. This decision should not be construed as demeaning Rural's efforts in compiling its directory, but rather as making clear that copyright rewards originality, not effort. As this Court noted more than a century ago, "`great praise may be due to the plaintiffs for their industry and enterprise in publishing this paper, yet the law does not contemplate their being rewarded in this way.'" Baker v. Selden, 101 U. S., at 105.79
The judgment of the Court of Appeals is80
JUSTICE BLACKMUN concurs in the judgment.82
[*] Briefs of amici curiae urging reversal were filed for the Association of North American Directory Publishers et al. by Theodore Case Whitehouse; for the International Association of Cross Reference Directory Publishers by Richard D. Grauer and Kathleen McCree Lewis; and for the Third-Class Mail Association by Ian D. Volner.83
Briefs of amici curiae urging affirmance were filed for Ameritech et al. by Michael K. Kellogg, Charles Rothfeld, Douglas J. Kirk, Thomas P. Hester, and Harlan Sherwat; for the Association of American Publishers, Inc., by Robert G. Sugarman and R. Bruce Rich; for GTE Corp. by Kirk K. Van Tine, Richard M. Cahill, and Edward R. Sublett; for the National Telephone Cooperative Association by L. Marie Guillory and David Cosson; for the United States Telephone Association by Richard J. Rappaport and Keith P. Schoeneberger; and for West Publishing Co. by Vance K. Opperman and James E. Schatz.84
Briefs of amici curiae were filed for Bellsouth Corp. by Anthony B. Askew, Robert E. Richards, Walter H. Alford, and Vincent L. Sgrosso; for the Direct Marketing Association, Inc., by Robert L. Sherman; for Haines and Co., Inc., by Jeremiah D. McAuliffe, Bernard A. Barken, and Eugene Gressman; and for the Information Industry Association et al. by Steven J. Metalitz and Angela Burnett.85
[*] The Court ultimately rendered judgment for Associated Press on non-copyright grounds that are not relevant here. See 248 U. S., at 235, 241-242.
714 F.2d 1240 (1983)2
United States Court of Appeals, Third Circuit.
Argued March 17, 1983.
Decided August 30, 1983.
Rehearing and Rehearing Denied September 23, 1983.
Certiorari Dismissed January 4, 1984.
  Jack E. Brown (argued), Eugene D. Cohen, Joseph W. Mott, Lawrence G.D. Scarborough, Brown & Bain, P.A., Phoenix, Ariz., Edwin H. Taylor, Blakely, Sokoloff, Taylor & Zafman, Beverly Hills, Cal., Ronald L. Panitch, Jay K. Meadway, Seidel, Gonda, Goldhammer & Panitch, P.C., Philadelphia, Pa., for appellant.5
Jerome J. Shestack (argued), Michael J. Mangan, Sherry A. Swirsky, Schnader, Harrison, Segal & Lewis, Manny D. Pokotilow, Barry A. Stein, Caesar, Rivise, Bernstein & Cohen, Ltd., Philadelphia, Pa., for appellee.6
Before HUNTER, HIGGINBOTHAM and SLOVITER, Circuit Judges.7
Rehearing and Rehearing In Banc Denied September 23, 1983.8
Certiorari Dismissed January 4, 1984. See 104 S.Ct. 690.9
Apple Computer, Inc. appeals from the district court's denial of a motion to preliminarily enjoin Franklin Computer Corp. from infringing the copyrights Apple holds on fourteen computer programs.14
The decision to grant or refuse to grant a preliminary injunction is within the discretion of the district court. See A.O. Smith Corp. v. FTC, 530 F.2d 515, 525 (3d Cir.1976). Although the scope of our review of the action of the district court in ruling on a motion for preliminary injunction is narrow, reversal is warranted if the trial court has abused its discretion or committed error in applying the law. Kennecott Corp. v. Smith, 637 F.2d 181, 187 (3d Cir.1980). As the Second Circuit has stated recently, "Despite oft repeated statements that the issuance of a preliminary injunction rests in the discretion of the trial judge whose decisions will be reversed only for `abuse', a court of appeals must reverse if the district court has proceeded on the basis of an erroneous view of the applicable law." Donovan v. Bierwirth, 680 F.2d 263, 269 (2d Cir.), cert. denied, ___ U.S. ___, 103 S.Ct. 488, 74 L.Ed.2d 631 (1982).15
In this case the district court denied the preliminary injunction, inter alia, because it had "some doubt as to the copyrightability of the programs." Apple Computer, Inc. v. Franklin Computer Corp., 545 F.Supp. 812, 812 (E.D.Pa.1982). This legal ruling is fundamental to all future proceedings in this action and, as the parties and amici curiae seem to agree, has considerable significance to the computer services industry. Because we conclude that the district court proceeded under an erroneous view of the applicable law, we reverse the denial of the preliminary injunction and remand.16
Apple, one of the computer industry leaders, manufactures and markets personal computers (microcomputers), related peripheral equipment such as disk drives (peripherals), and computer programs (software). It presently manufactures Apple II computers and distributes over 150 programs. Apple has sold over 400,000 Apple II computers, employs approximately 3,000 people, and had annual sales of $335,000,000 for fiscal year 1981. One of the byproducts of Apple's success is the independent development by third parties of numerous computer programs which are designed to run on the Apple II computer.19
 Franklin, the defendant below, manufactures and sells the ACE 100 personal computer and at the time of the hearing employed about 75 people and had sold fewer than 1,000 computers. The ACE 100 was designed to be "Apple compatible," so that peripheral equipment and software developed for use with the Apple II computer could be used in conjunction with the ACE 100. Franklin's copying of Apple's operating system computer programs in an effort to achieve such compatibility precipitated this suit.20
Like all computers both the Apple II and ACE 100 have a central processing unit (CPU) which is the integrated circuit that executes programs. In lay terms, the CPU does the work it is instructed to do. Those instructions are contained on computer programs.21
There are three levels of computer language in which computer programs may be written. High level language, such as the commonly used BASIC or FORTRAN, uses English words and symbols, and is relatively easy to learn and understand (e.g., "GO TO 40" tells the computer to skip intervening steps and go to the step at line 40). A somewhat lower level language is assembly language, which consists of alphanumeric labels (e.g., "ADC" means "add with carry"). Statements in high level language, and apparently also statements in assembly language, are referred to as written in "source code." The third, or lowest level computer language, is machine language, a binary language using two symbols, 0 and 1, to indicate an open or closed switch (e.g., "01101001" means, to the Apple, add two numbers and save the result). Statements in machine language are referred to as written in "object code."22
The CPU can only follow instructions written in object code. However, programs are usually written in source code which is more intelligible to humans. Programs written in source code can be converted or translated by a "compiler" program into object code for use by the computer. Programs are generally distributed only in their object code version stored on a memory device.23
A computer program can be stored or fixed on a variety of memory devices, two of which are of particular relevance for this case. The ROM (Read Only Memory) is an internal permanent memory device consisting of a semi-conductor "chip" which is incorporated into the circuitry of the computer. A program in object code is embedded on a ROM before it is incorporated in the computer. Information stored on a ROM can only be read, not erased or rewritten. The ACE 100 apparently contains EPROMS (Erasable Programmable Read Only Memory) on which the stored information can be erased and the chip reprogrammed, but the district court found that for purposes of this proceeding, the difference between ROMs and EPROMs is inconsequential. 545 F.Supp. at 813 n. 3. The other device used for storing the programs at issue is a diskette or "floppy disk", an auxiliary memory device consisting of a flexible magnetic disk resembling a phonograph record, which can be inserted into the computer and from which data or instructions can be read.24
Computer programs can be categorized by function as either application programs or operating system programs. Application programs usually perform a specific task for the computer user, such as word processing, checkbook balancing, or playing a game. In contrast, operating system programs generally manage the internal functions of the computer or facilitate use of application programs. The parties agree that the fourteen computer programs at  issue in this suit are operating system programs.25
Apple filed suit in the United States District Court for the Eastern District of Pennsylvania pursuant to 28 U.S.C. § 1338 on May 12, 1982, alleging that Franklin was liable for copyright infringement of the fourteen computer programs, patent infringement, unfair competition, and misappropriation. Franklin's answer in respect to the copyright counts included the affirmative defense that the programs contained no copyrightable subject matter. Franklin counterclaimed for declaratory judgment that the copyright registrations were invalid and unenforceable, and sought affirmative relief on the basis of Apple's alleged misuse. Franklin also moved to dismiss eleven of the fourteen copyright infringement counts on the ground that Apple failed to comply with the procedural requirements for suit under 17 U.S.C. §§ 410, 411.26
 After expedited discovery, Apple moved for a preliminary injunction to restrain Franklin from using, copying, selling, or infringing Apple's copyrights. The district court held a three day evidentiary hearing limited to the copyright infringement claims. Apple produced evidence at the hearing in the form of affidavits and testimony that programs sold by Franklin in conjunction with its ACE 100 computer were virtually identical with those covered by the fourteen Apple copyrights. The variations that did exist were minor, consisting merely of such things as deletion of reference to Apple or its copyright notice. James Huston, an Apple systems programmer, concluded that the Franklin programs were "unquestionably copied from Apple and could not have been independently created." He reached this conclusion not only because it is "almost impossible for so many lines of code" to be identically written, but also because his name, which he had embedded in one program (Master Create), and the word "Applesoft", which was embedded in another (DOS 3.3), appeared on the Franklin master disk. Apple estimated the "works in suit" took 46 man-months to produce at a cost of over $740,000, not including the time or cost of creating or acquiring earlier versions of the programs or the expense of marketing the programs.27
Franklin did not dispute that it copied the Apple programs. Its witness admitted copying each of the works in suit from the Apple programs. Its factual defense was directed to its contention that it was not feasible for Franklin to write its own operating system programs. David McWherter, now Franklin's vice-president of engineering, testified he spent 30-40 hours in November 1981 making a study to determine if it was feasible for Franklin to write its own Autostart ROM program and concluded it was not because "there were just too many entry points in relationship to the number of instructions in the program." Entry points at specific locations in the program can be used by programmers to mesh their application programs with the operating system program. McWherter concluded that use of the identical signals was necessary in order to ensure 100% compatibility with application programs created to run on the Apple computer. He admitted that he never attempted to rewrite Autostart ROM and conceded that some of the works in suit (i.e. Copy, Copy A, Master Create, and Hello) probably could have been rewritten by Franklin. Franklin made no attempt to rewrite any of the programs prior to the lawsuit except for Copy, although McWherter testified that Franklin was "in the process of redesigning" some of the Apple programs and that "[w]e had a fair degree of certainty that that would probably work." Apple introduced evidence that Franklin could have rewritten programs, including the Autostart ROM program, and that there are in existence operating programs written by third parties which are compatible with Apple II.28
Franklin's principal defense at the preliminary injunction hearing and before us is primarily a legal one, directed to its contention that the Apple operating system programs are not capable of copyright protection.29
The district court denied the motion for preliminary injunction by order and opinion dated July 30, 1982. Apple moved for reconsideration in light of this court's decision in Williams Electronics, Inc. v. Artic International, Inc., 685 F.2d 870 (3d Cir.1982), which was decided August 2, 1982, three days after the district court decision. The district court denied the motion for reconsideration. We have jurisdiction of Apple's appeal pursuant to 28 U.S.C. § 1292(a)(1).30
In its opinion, the district court referred to the four factors to be considered on  request for a preliminary injunction: a reasonable probability of success on the merits; irreparable injury; the improbability of harm to other interested persons; and the public interest. 545 F.Supp. at 825; see Delaware River Port Authority v. Transamerican Trailer Transport, Inc., 501 F.2d 917, 919-20 (3d Cir.1974). The court stated it based its denial of the motion on the first two factors. The court held Apple had not made the requisite showing of likelihood of success on the merits because it "concluded that there is some doubt as to the copyrightability of the programs described in this litigation." 545 F.Supp. at 812. It also stated that "Apple is better suited to withstand whatever injury it might sustain during litigation than is Franklin to withstand the effects of a preliminary injunction" because an injunction would have a "devastating effect" on Franklin's business, id. at 825, apparently concluding on that basis that Apple had failed to show irreparable harm.33
It is difficult to discern precisely why the district court questioned the copyrightability of the programs at issue since there is no finding, statement, or holding on which we can focus which clearly sets forth the district court's view. Throughout the opinion the district court referred to the "complexity of the question presented by the present case", 545 F.Supp. at 824, and the "baffling" problem at issue. Id. at 822.34
The opinion expresses a series of generalized concerns which may have led the court to its ultimate conclusion, and which the parties and amici treat as holdings. The district court referred to the requirement under the Copyright Act of finding "original works of authorship", 17 U.S.C. § 102(a), and seems to have found that there was a sufficient "modicum of creativity" to satisfy the statutory requirement of an "original work". 545 F.Supp. at 820-21. The court was less clear as to whether the creation of a computer program by a programmer satisfied the requirement of "works of authorship", id., and whether an operating system program in "binary code or one represented either in a ROM or by micro-switches" was an "expression" which could be copyrighted as distinguished from an "idea" which could not be. Id. at 821.35
Again, although we cannot point to a specific holding, running throughout the district court opinion is the suggestion that programs in object code and ROMs may not be copyrightable. Thus, for example, in a series of discursive footnotes, the district court stated that it found "persuasive" a district court opinion "holding that object code in ROM is not copyright protected", 545 F.Supp. at 818 n. 8 (referring to Data Cash Systems, Inc. v. JS & A Group, Inc., 480 F.Supp. 1063 (N.D.Ill.1979), aff'd on other grounds, 628 F.2d 1038 (7th Cir.1980)); described an opinion reaching a contrary conclusion as containing "rather terse analysis [which] provides little guidance", 545 F.Supp. at 818 n. 8 (referring to GCA Corp. v. Chance, 217 U.S.P.Q. 718 (N.D.Cal.1982), which followed the reasoning of Tandy Corp. v. Personal Micro Computers, Inc., 524 F.Supp. 171 (N.D.Cal.1981)), and stated that "Congressional intent regarding the copyrightability of object codes and ROMs is not clear", 545 F.Supp. at 819, n. 9, and that even among members of the industry it was not clear that the copyright law protects works "like those in suit that are ROM-based," id. at 819 n. 10.36
We read the district court opinion as presenting the following legal issues: (1) whether copyright can exist in a computer program expressed in object code, (2) whether copyright can exist in a computer program embedded on a ROM, (3) whether copyright can exist in an operating system program, and (4) whether independent irreparable harm must be shown for a preliminary injunction in copyright infringement actions.37
Certain statements by the district court suggest that programs expressed in object  code, as distinguished from source code, may not be the proper subject of copyright. We find no basis in the statute for any such concern. Furthermore, our decision in Williams Electronics, Inc. v. Artic International, Inc., supra, laid to rest many of the doubts expressed by the district court.42
In 1976, after considerable study, Congress enacted a new copyright law to replace that which had governed since 1909. Act of October 19, 1976, Pub.L. No. 94-553, 90 Stat. 2541 (codified at 17 U.S.C. §§ 101 et seq.). Under the law, two primary requirements must be satisfied in order for a work to constitute copyrightable subject matter — it must be an "original wor[k] of authorship" and must be "fixed in [a] tangible medium of expression." 17 U.S.C. § 102(a). The statute provides:43
(a) Copyright protection subsists, in accordance with this title, in original works of authorship fixed in any tangible medium of expression, now known or later developed, from which they can be perceived, reproduced, or otherwise communicated, either directly or with the aid of a machine or device.
Id. The statute enumerates seven categories under "works of authorship" including "literary works", defined as follows:45
"Literary works" are works, other than audiovisual works, expressed in words, numbers, or other verbal or numerical symbols or indicia, regardless of the nature of the material objects, such as books, periodicals, manuscripts, phonorecords, film, tapes, disks, or cards, in which they are embodied.
17 U.S.C. § 101. A work is "fixed" in a tangible medium of expression when:47
its embodiment in a copy or phonorecord, by or under the authority of the author, is sufficiently permanent or stable to permit it to be perceived, reproduced, or otherwise communicated for a period of more than transitory duration. A work consisting of sounds, images, or both, that are being transmitted, is "fixed" for purposes of this title if a fixation of the work is being made simultaneously with its transmission.
Although section 102(a) does not expressly list computer programs as works of authorship, the legislative history suggests that programs were considered copyrightable as literary works. See H.R.Rep. No. 1476, 94th Cong., 2d Sess. 54, reprinted in 1976 U.S.Code Cong. & Ad.News 5659, 5667 ("`literary works' ... includes ... computer programs"). Because a Commission on New Technological Uses ("CONTU") had been created by Congress to study, inter alia, computer uses of copyrighted works, Pub.L. No. 93-573, § 201, 88 Stat. 1873 (1974), Congress enacted a status quo provision, section 117, in the 1976 Act concerning such computer uses pending the CONTU report and recommendations.50
The CONTU Final Report recommended that the copyright law be amended, inter alia, "to make it explicit that computer programs, to the extent that they embody an author's original creation, are proper subject matter of copyright." National Commission on New Technological Uses of Copyrighted Works, Final Report 1 (1979) [hereinafter CONTU Report]. CONTU recommended two changes relevant here: that section 117, the status quo provision, be repealed and replaced with a section limiting exclusive rights in computer programs so as "to ensure that rightful possessors of copies of computer programs may use or adapt these copies for their use," id.; and that a definition of computer program be added to section 101. Id. at 12. Congress adopted both changes. Act of Dec. 12, 1980, Pub.L. No. 96-517, § 10, 94 Stat. 3015, 3028. The revisions embodied CONTU's recommendations to clarify the law of copyright of computer software. H.R.Rep. No. 1307, 96th Cong., 2d Sess. 23, reprinted in 1980 U.S.Code Cong. & Ad.News 6460, 6482.51
The 1980 amendments added a definition of a computer program:52
 A "computer program" is a set of statements or instructions to be used directly or indirectly in a computer in order to bring about a certain result.
17 U.S.C. § 101. The amendments also substituted a new section 117 which provides that "it is not an infringement for the owner of a copy of a computer program to make or authorize the making of another copy or adaptation of that computer program" when necessary to "the utilization of the computer program" or "for archival purposes only." 17 U.S.C. § 117. The parties agree that this section is not implicated in the instant lawsuit. The language of the provision, however, by carving out an exception to the normal proscriptions against copying, clearly indicates that programs are copyrightable and are otherwise afforded copyright protection.54
We considered the issue of copyright protection for a computer program in Williams Electronics, Inc. v. Artic International, Inc., and concluded that "the copyrightability of computer programs is firmly established after the 1980 amendment to the Copyright Act." 685 F.2d at 875. At issue in Williams were not only two audiovisual copyrights to the "attract" and "play" modes of a video game, but also the computer program which was expressed in object code embodied in ROM and which controlled the sights and sounds of the game. Defendant there had argued "that when the issue is the copyright on a computer program, a distinction must be drawn between the `source code' version of a computer program, which ... can be afforded copyright protection, and the `object code' stage, which ... cannot be so protected," an argument we rejected. Id. at 876.55
The district court here questioned whether copyright was to be limited to works "designed to be `read' by a human reader [as distinguished from] read by an expert with a microscope and patience", 545 F.Supp. at 821. The suggestion that copyrightability depends on a communicative function to individuals stems from the early decision of White-Smith Music Publishing Co. v. Apollo Co., 209 U.S. 1, 28 S.Ct. 319, 52 L.Ed. 655 (1908), which held a piano roll was not a copy of the musical composition because it was not in a form others, except perhaps for a very expert few, could perceive. See 1 Nimmer on Copyright § 2.03[B] (1983). However, it is clear from the language of the 1976 Act and its legislative history that it was intended to obliterate distinctions engendered by White-Smith. H.R.Rep. No. 1476, supra, at 52, reprinted in 1976 U.S.Code Cong. & Ad.News at 5665.56
Under the statute, copyright extends to works in any tangible means of expression "from which they can be perceived, reproduced, or otherwise communicated, either directly or with the aid of a machine or device." 17 U.S.C. § 102(a) (emphasis added). Further, the definition of "computer program" adopted by Congress in the 1980 amendments is "sets of statements or instructions to be used directly or indirectly in a computer in order to bring about a certain result." 17 U.S.C. § 101 (emphasis added). As source code instructions must be translated into object code before the computer can act upon them, only instructions expressed in object code can be used "directly" by the computer. See Midway Manufacturing Co. v. Strohon, 564 F.Supp. 741 at 750-751 (N.D.Ill.1983). This definition was adopted following the CONTU Report in which the majority clearly took the position that object codes are proper subjects of copyright. See CONTU Report at 21. The majority's conclusion was reached although confronted by a dissent based upon the theory that the "machine-control phase" of a program is not directed at a human audience. See CONTU Report at 28-30 (dissent of Commissioner Hersey).57
The defendant in Williams had also argued that a copyrightable work "must be intelligible to human beings and must be intended as a medium of communication to human beings," id. at 876-77. We reiterate the statement we made in Williams when we rejected that argument: "[t]he answer to defendant's contention is in the words of the statute itself." 685 F.2d at 877.58
 The district court also expressed uncertainty as to whether a computer program in object code could be classified as a "literary work." However, the category of "literary works", one of the seven copyrightable categories, is not confined to literature in the nature of Hemingway's For Whom the Bell Tolls. The definition of "literary works" in section 101 includes expression not only in words but also "numbers, or other ... numerical symbols or indicia", thereby expanding the common usage of "literary works." Cf. Harcourt, Brace & World, Inc. v. Graphic Controls Corp., 329 F.Supp. 517, 523-24 (S.D.N.Y.1971) (the symbols designating questions or response spaces on exam answer sheets held to be copyrightable "writings" under 1909 Act); Reiss v. National Quotation Bureau, Inc., 276 F. 717 (S.D.N.Y.1921) (code book of coined words designed for cable use copyrightable). Thus a computer program, whether in object code or source code, is a "literary work" and is protected from unauthorized copying, whether from its object or source code version. Accord Midway Mfg. Co. v. Strohon, 564 F.Supp. at 750-751; see also GCA Corp. v. Chance, 217 U.S.P.Q. at 719-20.59
Just as the district court's suggestion of a distinction between source code and object code was rejected by our opinion in Williams issued three days after the district court opinion, so also was its suggestion that embodiment of a computer program on a ROM, as distinguished from in a traditional writing, detracts from its copyrightability. In Williams we rejected the argument that "a computer program is not infringed when the program is loaded into electronic memory devices (ROMs) and used to control the activity of machines." 685 F.2d at 876. Defendant there had argued that there can be no copyright protection for the ROMs because they are utilitarian objects or machine parts. We held that the statutory requirement of "fixation", the manner in which the issue arises, is satisfied through the embodiment of the expression in the ROM devices. Id. at 874, 876; see also Midway Mfg. Co. v. Strohon, 564 F.Supp. at 751-752; Tandy Corp. v. Personal Micro Computers, Inc., 524 F.Supp. at 173; cf. Stern Electronics, Inc. v. Kaufman, 669 F.2d 852, 855-56 (2d Cir.1982) (audiovisual display of video game "fixed" in ROM). Therefore we reaffirm that a computer program in object code embedded in a ROM chip is an appropriate subject of copyright. See also Note, Copyright Protection of Computer Program Object Code, 96 Harv.L.Rev. 1723 (1983); Note, Copyright Protection for Computer Programs in Read Only Memory Chips, 11 Hofstra L.Rev. 329 (1982).62
We turn to the heart of Franklin's position on appeal which is that computer operating system programs, as distinguished from application programs, are not the proper subject of copyright "regardless of the language or medium in which they are fixed." Brief of Appellee at 15 (emphasis deleted). Apple suggests that this issue too is foreclosed by our Williams decision because some portion of the program at issue there was in effect an operating system program. Franklin is correct that this was not an issue raised by the parties in Williams and it was not considered by the  court. Thus we consider it as a matter of first impression.65
Franklin contends that operating system programs are per se excluded from copyright protection under the express terms of section 102(b) of the Copyright Act, and under the precedent and underlying principles of Baker v. Selden, 101 U.S. 99, 25 L.Ed. 841 (1879). These separate grounds have substantial analytic overlap.66
In Baker v. Selden, plaintiff's testator held a copyright on a book explaining a bookkeeping system which included blank forms with ruled lines and headings designed for use with that system. Plaintiff sued for copyright infringement on the basis of defendant's publication of a book containing a different arrangement of the columns and different headings, but which used a similar plan so far as results were concerned. The Court, in reversing the decree for the plaintiff, concluded that blank account-books were not the subject of copyright and that "the mere copyright of Selden's book did not confer upon him the exclusive right to make and use account-books, ruled and arranged as designated by him and described and illustrated in said book." Id. at 107. The Court stated that copyright of the books did not give the plaintiff the exclusive right to use the system explained in the books, noting, for example, that "copyright of a work on mathematical science cannot give to the author an exclusive right to the methods of operation which he propounds." Id. at 103.67
Franklin reads Baker v. Selden as "stand[ing] for several fundamental principles, each presenting ... an insuperable obstacle to the copyrightability of Apple's operating systems." It states:68
First, Baker teaches that use of a system itself does not infringe a copyright on the description of the system. Second, Baker enunciates the rule that copyright does not extend to purely utilitarian works. Finally, Baker emphasizes that the copyright laws may not be used to obtain and hold a monopoly over an idea. In so doing, Baker highlights the principal difference between the copyright and patent laws — a difference that is highly pertinent in this case.
Brief of Appellee at 22.70
Section 102(b) of the Copyright Act, the other ground on which Franklin relies, appeared first in the 1976 version, long after the decision in Baker v. Selden. It provides:71
In no case does copyright protection for an original work of authorship extend to any idea, procedure, process, system, method of operation, concept, principle, or discovery, regardless of the form in which it is described, explained, illustrated, or embodied in such work.
It is apparent that section 102(b) codifies a substantial part of the holding and dictum of Baker v. Selden. See 1 Nimmer on Copyright § 2.18[D], at 2-207.73
We turn to consider the two principal points of Franklin's argument.74
Franklin argues that an operating system program is either a "process", "system", or "method of operation" and hence uncopyrightable. Franklin correctly notes that underlying section 102(b) and many of the statements for which Baker v. Selden is cited is the distinction which must be made between property subject to the patent law, which protects discoveries, and that subject to copyright law, which protects the writings describing such discoveries. However,  Franklin's argument misapplies that distinction in this case. Apple does not seek to copyright the method which instructs the computer to perform its operating functions but only the instructions themselves. The method would be protected, if at all, by the patent law, an issue as yet unresolved. See Diamond v. Diehr, 450 U.S. 175, 101 S.Ct. 1048, 67 L.Ed.2d 155 (1981).76
Franklin's attack on operating system programs as "methods" or "processes" seems inconsistent with its concession that application programs are an appropriate subject of copyright. Both types of programs instruct the computer to do something. Therefore, it should make no difference for purposes of section 102(b) whether these instructions tell the computer to help prepare an income tax return (the task of an application program) or to translate a high level language program from source code into its binary language object code form (the task of an operating system program such as "Applesoft", see note 4 supra). Since it is only the instructions which are protected, a "process" is no more involved because the instructions in an operating system program may be used to activate the operation of the computer than it would be if instructions were written in ordinary English in a manual which described the necessary steps to activate an intricate complicated machine. There is, therefore, no reason to afford any less copyright protection to the instructions in an operating system program than to the instructions in an application program.77
Franklin's argument, receptively treated by the district court, that an operating system program is part of a machine mistakenly focuses on the physical characteristics of the instructions. But the medium is not the message. We have already considered and rejected aspects of this contention in the discussion of object code and ROM. The mere fact that the operating system program may be etched on a ROM does not make the program either a machine, part of a machine or its equivalent. Furthermore, as one of Franklin's witnesses testified, an operating system does not have to be permanently in the machine in ROM, but it may be on some other medium, such as a diskette or magnetic tape, where it could be readily transferred into the temporary memory space of the computer. In fact, some of the operating systems at issue were on diskette. As the CONTU majority stated,78
Programs should no more be considered machine parts than videotapes should be considered parts of projectors or phonorecords parts of sound reproduction equipment.... That the words of a program are used ultimately in the implementation of a process should in no way affect their copyrightability.
CONTU Report at 21.80
Franklin also argues that the operating systems cannot be copyrighted because they are "purely utilitarian works" and that Apple is seeking to block the use of the art embodied in its operating systems. This argument stems from the following dictum in Baker v. Selden:81
The very object of publishing a book on science or the useful arts is to communicate to the world the useful knowledge which it contains. But this object would be frustrated if the knowledge could not be used without incurring the guilt of piracy of the book. And where the art it teaches cannot be used without employing the methods and diagrams used to illustrate the book, or such as are similar to them, such methods and diagrams are to be considered as necessary incidents to the art, and given therewith to the public; not given for the purpose of publication in other works explanatory of the art, but for the purpose of practical application.
101 U.S. at 103. We cannot accept the expansive reading given to this language by some courts, see, e.g., Taylor Instrument Companies v. Fawley-Brost Co., 139 F.2d 98 (7th Cir.1943), cert. denied, 321 U.S. 785, 64 S.Ct. 782, 88 L.Ed. 1076 (1944). In this respect we agree with the views expressed by Professor Nimmer in his treatise. See 1 Nimmer on Copyright § 2.18[C].83
 Although a literal construction of this language could support Franklin's reading that precludes copyrightability if the copyright work is put to a utilitarian use, that interpretation has been rejected by a later Supreme Court decision. In Mazer v. Stein, 347 U.S. 201, 218, 74 S.Ct. 460, 471, 98 L.Ed. 630 (1954), the Court stated: "We find nothing in the copyright statute to support the argument that the intended use or use in industry of an article eligible for copyright bars or invalidates its registration. We do not read such a limitation into the copyright law." Id. at 218, 74 S.Ct. at 471. The CONTU majority also rejected the expansive view some courts have given Baker v. Selden, and stated, "That the words of a program are used ultimately in the implementation of a process should in no way affect their copyrightability." Id. at 21. It referred to "copyright practice past and present, which recognizes copyright protection for a work of authorship regardless of the uses to which it may be put." Id. The Commission continued: "The copyright status of the written rules for a game or a system for the operation of a machine is unaffected by the fact that those rules direct the actions of those who play the game or carry out the process." Id. (emphasis added). As we previously noted, we can consider the CONTU Report as accepted by Congress since Congress wrote into the law the majority's recommendations almost verbatim. See 18 Cong.Rec. H10767 (daily ed. Nov. 17, 1980) (Rep. Kastenmeier: Bill "eliminates confusion about the legal status of computer software by enacting the recommendations of [CONTU] clarifying the law of copyright of computer software"); 18 Cong.Rec. S14766 (daily ed. Nov. 20, 1980) (Sen. Bayh: "[t]his language reflects that proposed by [CONTU"]).84
Perhaps the most convincing item leading us to reject Franklin's argument is that the statutory definition of a computer program as a set of instructions to be used in a computer in order to bring about a certain result, 17 U.S.C. § 101, makes no distinction between application programs and operating programs. Franklin can point to no decision which adopts the distinction it seeks to make. In the one other reported case to have considered it, Apple Computer, Inc. v. Formula International, Inc., 562 F.Supp. 775 (C.D.Cal.1983), the court reached the same conclusion which we do, i.e. that an operating system program is not per se precluded from copyright. It stated, "There is nothing in any of the statutory terms which suggest a different result for different types of computer programs based upon the function they serve within the machine." Id. at 780. Other courts have also upheld the copyrightability of operating programs without discussion of this issue. See Tandy Corp. v. Personal Micro Computers, Inc., 524 F.Supp. at 173 (input-output routine stored in ROM which translated input into machine language in a similar fashion as Applesoft and Apple Integer Basic proper subject of copyright); GCA Corp. v. Chance, 217 U.S.P.Q. at 719-20 (object code version of registered source code version of operating programs is the same work and protected).85
Franklin's other challenge to copyright of operating system programs relies on the line which is drawn between ideas and their expression. Baker v. Selden remains a benchmark in the law of copyright for the reading given it in Mazer v. Stein, supra, where the Court stated, "Unlike a patent, a copyright gives no exclusive right to the art disclosed; protection is given only to the expression of the idea — not the idea itself." 347 U.S. at 217, 74 S.Ct. at 470 (footnote omitted).87
The expression/idea dichotomy is now expressly recognized in section 102(b) which precludes copyright for "any idea." This provision was not intended to enlarge or contract the scope of copyright protection but "to restate ... that the basic dichotomy between expression and idea remains unchanged." H.R.Rep. No. 1476, supra, at 57, reprinted in 1976 U.S.Code Cong. & Ad.News at 5670. The legislative history indicates that section 102(b) was intended "to make clear that the expression adopted by the programmer is the copyrightable element  in a computer program, and that the actual processes or methods embodied in the program are not within the scope of the copyright law." Id.88
Many of the courts which have sought to draw the line between an idea and expression have found difficulty in articulating where it falls. See, e.g., Nichols v. Universal Pictures Corp., 45 F.2d 119, 121 (2d Cir.1930) (L. Hand, J.); see discussion in 3 Nimmer on Copyright § 13.03[A]. We believe that in the context before us, a program for an operating system, the line must be a pragmatic one, which also keeps in consideration "the preservation of the balance between competition and protection reflected in the patent and copyright laws". Herbert Rosenthal Jewelry Corp. v. Kalpakian, 446 F.2d 738, 742 (9th Cir.1971). As we stated in Franklin Mint Corp. v. National Wildlife Art Exchange, Inc., 575 F.2d 62, 64 (3d Cir.), cert. denied, 439 U.S. 880, 99 S.Ct. 217, 58 L.Ed.2d 193 (1978), "Unlike a patent, a copyright protects originality rather than novelty or invention." In that opinion, we quoted approvingly the following passage from Dymow v. Bolton, 11 F.2d 690, 691 (2d Cir.1926):89
Just as a patent affords protection only to the means of reducing an inventive idea to practice, so the copyright law protects the means of expressing an idea; and it is as near the whole truth as generalization can usually reach that, if the same idea can be expressed in a plurality of totally different manners, a plurality of copyrights may result, and no infringement will exist.
We adopt the suggestion in the above language and thus focus on whether the idea is capable of various modes of expression. If other programs can be written or created which perform the same function as an Apple's operating system program, then that program is an expression of the idea and hence copyrightable. In essence, this inquiry is no different than that made to determine whether the expression and idea have merged, which has been stated to occur where there are no or few other ways of expressing a particular idea. See, e.g., Morrissey v. Procter & Gamble Co., 379 F.2d 675, 678-79 (1st Cir.1967); Freedman v. Grolier Enterprises, Inc., 179 U.S.P.Q. 476, 478 (S.D.N.Y.1973) ("[c]opyright protection will not be given to a form of expression necessarily dictated by the underlying subject matter"); CONTU Report at 20.92
The district court made no findings as to whether some or all of Apple's operating programs represent the only means of expression of the idea underlying them. Although there seems to be a concession by Franklin that at least some of the programs can be rewritten, we do not believe that the record on that issue is so clear that it can be decided at the appellate level. Therefore, if the issue is pressed on remand, the necessary finding can be made at that time.93
Franklin claims that whether or not the programs can be rewritten, there are a limited "number of ways to arrange operating systems to enable a computer to run the vast body of Apple-compatible software", Brief of Appellee at 20. This claim has no pertinence to either the idea/expression dichotomy or merger. The idea which may merge with the expression, thus making the copyright unavailable, is the idea which is the subject of the expression. The idea of one of the operating system programs is, for example, how to translate source code into object code. If other methods of expressing that idea are not foreclosed as a practical matter, then there is no merger. Franklin may wish to achieve total compatibility with independently developed application programs written for the Apple II, but that is a commercial and competitive objective which does not enter into the somewhat metaphysical issue of whether particular ideas and expressions have merged.94
In summary, Franklin's contentions that operating system programs are per se not copyrightable is unpersuasive. The other courts before whom this issue has been raised have rejected the distinction. Neither the CONTU majority nor Congress made a distinction between operating and application programs. We believe that the  1980 amendments reflect Congress' receptivity to new technology and its desire to encourage, through the copyright laws, continued imagination and creativity in computer programming. Since we believe that the district court's decision on the preliminary injunction was, to a large part, influenced by an erroneous view of the availability of copyright for operating system programs and unnecessary concerns about object code and ROMs, we must reverse the denial of the preliminary injunction and remand for reconsideration.95
The district court, without any extended discussion, found that Apple had not made the requisite showing of irreparable harm, stating "Apple is better suited to withstand whatever injury it might sustain during litigation than is Franklin to withstand the effects of a preliminary injunction." 545 F.Supp. at 812, 825. In so ruling, the district court failed to consider the prevailing view that a showing of a prima facie case of copyright infringement or reasonable likelihood of success on the merits raises a presumption of irreparable harm. See, e.g., Atari, Inc. v. North American Philips Consumer Electronics Corp., 672 F.2d 607, 620 (7th Cir.), cert. denied, ___ U.S. ___, 103 S.Ct. 176, 74 L.Ed.2d 145 (1982); Wainwright Securities Inc. v. Wall Street Transcript Corp., 558 F.2d 91, 94 (2d Cir.1977), cert. denied, 434 U.S. 1014, 98 S.Ct. 730, 54 L.Ed.2d 759 (1978); Klitzner Industries, Inc. v. H.K. James & Co., 535 F.Supp. 1249, 1259 (E.D.Pa.1982); Custom Decor, Inc. v. Nautical Crafts Inc., 502 F.Supp. 154, 157 (E.D.Pa.1980). A copyright plaintiff who makes out a prima facie case of infringement is entitled to a preliminary injunction without a detailed showing of irreparable harm. See 3 Nimmer on Copyright § 14.06[A], at 14-50, 14-51 & n. 16 (collecting authorities).98
The CONTU Final Report recognized that "[t]he cost of developing computer programs is far greater than the cost of their duplication." CONTU Report at 11. Apple introduced substantial evidence of the considerable time and money it had invested in the development of the computer programs in suit. Thus even without the presumption of irreparable harm generally applied in copyright infringement cases, the jeopardy to Apple's investment and competitive position caused by Franklin's wholesale copying of many of its key operating programs would satisfy the requirement of irreparable harm needed to support a preliminary injunction. See Atari, Inc. v. North American Philips Consumer Electronics Corp., 672 F.2d at 620; Custom Decor, Inc. v. Nautical Crafts Inc., 502 F.Supp. 154, 157 (E.D.Tenn.1980); Herbert Rosenthal Jewelry Corp. v. Zale Corp., 323 F.Supp. 1234, 1238 (S.D.N.Y.1971).99
In Kontes Glass Co. v. Lab Glass, Inc., 373 F.2d 319, 320-21 (3d Cir.1967), this court appeared to adopt an inverse relationship approach to the irreparable harm issue, suggesting that the strength of the required showing of irreparable injury varies inversely with the strength of plaintiff's showing of a likelihood of success on the merits. See Midway Mfg. Co. v. Bandai-America, Inc., 546 F.Supp. 125, 141-42 (D.N.J.1982). In Kontes, we were not presented with a case in which copyrighted material central to the essence of plaintiff's operations was concededly copied, as we are here. We believe the Kontes approach is best suited to those cases where the injury from copying can be fairly considered minimal, limited or conjectural. In those circumstances it provides flexibility in applying the equitable remedy of preliminary injunctions through evaluation of the irreparable harm factor. Normally, however, the public interest underlying the copyright law requires a presumption of irreparable harm, as long as there is, as here, adequate evidence of the expenditure of significant time, effort and money directed to the production of the copyrighted material. Otherwise, the rationale for protecting copyright, that of encouraging creativity, would be undermined. As Judge Broderick stated in Klitzner Industries, Inc. v. H.K. James & Co., 535 F.Supp. at 1259-60:100
 Since Congress has elected to grant certain exclusive rights to the owner of a copyright in a protected work, it is virtually axiomatic that the public interest can only be served by upholding copyright protections and, correspondingly, preventing the misappropriation of the skills, creative energies, and resources which are invested in the protected work.
Nor can we accept the district court's explanation which stressed the "devastating effect" of a preliminary injunction on Franklin's business. If that were the correct standard, then a knowing infringer would be permitted to construct its business around its infringement, a result we cannot condone. See Atari, Inc. v. North American Philips Consumer Electronics Corp., 672 F.2d at 620; cf. Helene Curtis Industries, Inc. v. Church & Dwight Co., 560 F.2d 1325, 1333 (7th Cir.1977) (trademark infringement), cert. denied, 434 U.S. 1070, 98 S.Ct. 1252, 55 L.Ed.2d 772 (1978). The size of the infringer should not be determinative of the copyright holder's ability to get prompt judicial redress.102
Franklin has raised a number of issues concerning Apple's compliance with various statutory formalities such as registration, notice and deposit. It has challenged, in a pending motion to dismiss, the copyrights of the eleven works in suit which were deposited in object code format, and which were registered under the Copyright Office's "rule of doubt." Franklin challenges three programs, i.e. Apple Integer Basic, Autostart ROM and DOS 3.3, on the ground that they or their predecessors were published without the requisite notice. We do not reach these issues on appeal nor do we consider Franklin's claim that Apple's misuse of its copyrights bars their enforcement. The district court did not consider these claims in denying the motion for preliminary injunction. There are no factual findings with regard to them. On remand, they can be considered by the district court in the first instance who can also decide the extent to which they are relevant, if at all, to a preliminary injunction.105
For the reasons set forth in this opinion, we will reverse the denial of the preliminary injunction and remand to the district court for further proceedings in accordance herewith.107
 Four amicus curiae briefs have been submitted; briefs from Digital Research Inc., Microsoft Corp., and Association of Data Processing Service Organizations, Inc. (a trade association for the computer services industry), support the position of Apple, and a brief from Pro-log Corp. supports at least part of Franklin's position.108
 Useful nontechnical descriptions of computer operations appear in Note, Copyright Protection for Computer Programs In Read Only Memory Chips, 11 Hofstra L.Rev. 329 (1982), and Note, Copyright Protection of Computer Program Object Code, 96 Harv.L.Rev. 1723 (1983).109
 In contrast to the permanent memory devices a RAM (Random Access Memory) is a chip on which volatile internal memory is stored which is erased when the computer's power is turned off.110
 The fourteen programs at issue, briefly described, are:111
(1) Autostart ROM is sold as part of the Apple Computer and is embedded on a ROM chip. The program has also been published in source code as part of a copyrighted book, the Apple II manual. When the computer's power is turned on, Autostart ROM performs internal routines that turn on the circuits in the computer and make its physical parts (e.g. input/output devices, screen, and memory) ready for use.
(2) Applesoft is Apple's version of the Beginner's All-purpose Symbolic Instruction Code (BASIC) language. The program is stored in ROM and is sold as part of the computer. Applesoft translates instructions written in the higher-level BASIC language into the lower-level machine code that the computer understands.
(3) Floating-Point BASIC is the same program as Applesoft but is stored on disks rather than on ROMs. It is used in earlier versions of the Apple II computer that did not have the Applesoft program in ROM.
(4) Apple Integer BASIC, another translator program, is stored on the DOS 3.3 Master Disk. This program used Apple's first version of BASIC for the Apple II computer. It implements a simpler version of the Applesoft program.
(5) DOS 3.3, the disk operating system program, provides the instructions necessary to control the operation between the disk system (disk drive) and the computer itself. It controls the reading and writing functions of the disks and includes other routines which put all the data transfers in sequence. The DOS 3.3 Master Disk is sold separately from the computer, and includes several of the other operating programs referred to in this note.
(6) Master Create is stored on a disk. When a disk is prepared for use the DOS 3.3 program is placed on that disk in a form that is dependent on the amount of Random Access Memory (RAM) available. The Master Create program replaces the DOS 3.3 on the disk with a version that is independent of the amount of RAM available.
(7) Copy, which is stored on a disk, enables the user to copy programs written in Apple Integer BASIC from one disk to another.
(8) Copy A, also stored on a disk, enables the user to copy programs written in Applesoft from one disk to another.
(9) Copy OBJO contains a file of subroutines used by the Copy and Copy A programs.
(10) Chain, another disk stored program, allows data to be passed between different parts of a program when only one part of the program is in RAM at a given time. Thus, Chain preserves data already stored in RAM while another part of the program is being loaded into RAM.
(11) Hello, also disk stored, is the first program executed after the power is turned on and a disk is ready for use. It determines how much RAM is in the computer and which version of BASIC needs to be loaded into the computer.
(12) Boot 13 is stored on disk and sold on a Master Disk. It allows the user having a disk controller card that contains the Apple 16-Sector Boot ROM to use older versions of the Apple disk operating system.
(13) Apple 13-Sector Boot ROM is stored in a ROM located on the disk controller card plugged into the Mother Board. By turning on numerous circuits on the card and in the Apple II computer, this program causes other parts of the disk operating system used for 13-Sector format disks to load.
(14) Apple 16-Sector Boot ROM, stored in a ROM located on the disk controller card, turns on numerous circuits on the card and in the Apple II computer and causes other parts of the disk operating system used for 16-Sector format disks to load. It therefore enables the user to start or permit the running of another program or to prepare the computer to receive a program.
The above descriptions represent an effort to translate the language used by computer experts into language reasonably intelligible to lay persons. They differ in some respects from the descriptions in the district court's opinion, 545 F.Supp. at 815-16, which were taken from the complaint.113
 For example, 8 bytes of memory were altered in the Autostart ROM program so that when the computer is turned on "ACE 100" appears on the screen rather than "Apple II." The Franklin DOS 3.3 program also had 16 bytes (out of 9000) that allowed use of upper and lower case.114
 Section 117 applied only to the scope of protection to be accorded copyrighted works when used in conjunction with a computer and not to the copyrightability of programs. H.R.Rep. No. 1476, at 116, reprinted in 1976 U.S.Code Cong. & Ad.News at 5731.115
 The district court stated that a programmer working directly in object code appears to think more as a mathematician or engineer, that the process of constructing a chip is less a work of authorship than the product of engineering knowledge, and that it may be more apt to describe an encoded ROM as a pictorial three-dimensional object than as a literary work. 545 F.Supp. at 821-22. The district court's remarks relied in part on a quotation about "microcode", see id. at 821 n. 14; Apple introduced testimony that none of the works in suit contain "microcode." Moreover, Apple does not seek to protect the ROM's architecture but only the program encoded upon it.116
 We are unpersuaded by Franklin's initial contention that Apple is bound to this position because some of Apple's witnesses in the preliminary injunction hearing used these terms in describing the works in suit. As the CONTU Report itself recognized, the distinction between copyrightable computer programs and uncopyrightable processes or methods of operation does not always seem to "shimmer with clarity." CONTU Report at 18. The witnesses undoubtedly had the not uncommon difficulty of finding the precisely correct words of description in this field. It would be both unreasonable and arbitrary to consider the statements of non-lawyer witnesses without experience in using statutory language as words of art to be binding admissions against Apple.117
 Apparently the Register of Copyrights utilizes its rule of doubt when the deposit of a computer program is made in object code form because its examiners cannot interpret such code to determine if there has been copyrightable authorship.
81 F.3d 1576 (1996)2
United States Court of Appeals, Federal Circuit.
April 26, 1996.
  Kenneth J. Kelly, Epstein Becker & Green, P.C., New York City, argued for plaintiffs-appellants.5
Henry B. Gutman, Baker & Botts, L.L.P., New York City, argued for defendant-appellee. With him on the brief were Kerry L. Konrad, Jeffrey E. Ostrow, and Lori E. Lesser.6
Before ARCHER, Chief Judge, LOURIE, and CLEVENGER, Circuit Judges.7
Refac International, Ltd. and Forward Reference Systems, Ltd. ("FRS") appeal from the judgment of the United States District Court for the Southern District of New York holding that FRS's patent is unenforceable on the ground of inequitable conduct. REFAC Int'l, Ltd. v. Lotus Dev. Corp., 887 F.Supp. 539 (S.D.N.Y.1995). Because the district court did not make clearly erroneous factual findings or abuse its discretion in determining that the inventors, Rene K. Pardo and Remy Landau, engaged in inequitable conduct, we affirm.9
The patent in suit, U.S. Patent 4,398,249, concerns a method of converting a software source code program to object code. During prosecution of the '249 patent, the examiner initially rejected the application, which was filed on August 12, 1970, under 35 U.S.C. § 112, ¶ 1, on the ground of inadequate disclosure. In response, a Rule 132 affidavit by Pardo was submitted, averring that the application contained sufficient disclosure to enable any person skilled in the programming art to make and use the claimed invention. See 37 C.F.R. § 1.132 (1995) ("Affidavits or declarations traversing grounds of rejection."). In response, the examiner issued a final rejection, stating:11
[T]he disclosure is not deemed of the level which would enable one with ordinary skill in the art to make and use the invention. The flow diagram which applicants represent in figure 2 is not of the detailed level which a programmer would need in order to write a program from. The general outline shown in figure 2 will still have to be broken down into fundamentals of what is necessary to write a program.
The examiner's comment on the Pardo affidavit was as follows:13
It should be pointed out that an affidavit by applicant is self serving and therefore has very little probative value in a response to an objection that the specification is inadequately disclosed. By filing an application, applicants have indicated that it fulfills the statutory requirements set out in 35 U.S.C. 112, and an objection by the Examiner that the disclosure does not meet the conditions set out there, cannot be overcome by an affidavit by an applicant that it does.
A challenge by the Examiner should put an applicant to his proofs. A declaration by coapplicant is no more probative of the sufficiency of the disclosure than the specification as originally filed, which has been objected to.
The inventors' attorney, R. Gale Rhodes, Jr., proposed a strategy of filing affidavits from three people other than the inventors, with different experience and skill levels, attesting to the sufficiency of the disclosure. He requested that the inventors find three such people, and they recommended Peter H. Jones, a computer scientist or compiler writer; David H. Cikra, a computer programmer; and Robert F. Bullen, a supervisor of programmers. Affidavits from these three individuals were then filed, along with a Rule 116 amendment, which stated that "the present invention is directed to the computer scientist or compiler writer, not a mere programmer, and it is such compiler writer who is the man of `ordinary skill in the art' who would practice the invention as defined by the claims." See 37 C.F.R. § 1.116 (1995) ("Amendments after final action.").15
Each of the affidavits contained opinions or factual statements asserting the sufficiency of the application's disclosure. Bullen's affidavit stated that an average programmer could have written a computer program from the application's disclosure using programming techniques known before the application was filed. Cikra's affidavit stated that he had actually written a computer program  solely from the disclosure and had sufficiently tested the program to verify its operability. Jones's affidavit contained the following statement:16
[F]rom the written disclosures and flow chart shown in the drawing of such patent application, [I] could have produced as of August 12, 1970, and prior thereto, and using only programming techniques known on or prior to August 12, 1970, the necessary coding and could have written a detailed computer program therefrom.
In response to these affidavits, the examiner issued a notice of allowance. Neither the inventors nor the affiants had disclosed to the U.S. Patent and Trademark Office ("PTO"), however, that each of the affiants had a prior association with the inventors' company, Lanpar, Ltd., or that they had pre-existing knowledge of a commercial embodiment of the invention, the LANPAR program.18
After the '249 patent issued, the inventors assigned it to FRS, another company they controlled. FRS entered into an agreement with Refac, assigning it a five-percent interest in the '249 patent in exchange for Refac's obligation to sue at least two alleged infringers within one month. Refac and FRS agreed to split equally all proceeds from the litigation. On July 26, 1989, Refac sued six software publishers, including Lotus Development Corporation, alleging that their spreadsheet computer software programs infringed the '249 patent. After Refac amended its complaint to add FRS as a co-plaintiff, the action was dismissed against all defendants except Lotus. On July 29 and 30, 1993, the district court conducted a bench trial limited to Lotus's affirmative defense of inequitable conduct, and held that the patent was unenforceable on the ground of inequitable conduct, which occurred when the inventors submitted the Jones affidavit containing a material omission intended to mislead the PTO into granting the patent.19
The district court carefully evaluated each of the three affidavits. The court found that the Bullen affidavit failed to disclose that Bullen had a prior association with Landau. In particular, when Bullen was a consultant with UNIVAC Canada, he had worked with Landau, who was at the time a programmer employed by Bell Canada. The court found that the Bullen affidavit also failed to disclose that Pardo and Landau had informed Bullen, before he executed his affidavit, that a computer program implementing the invention was in use at Bell Canada. The court concluded that the submission to the PTO of the Bullen affidavit with this omission did not constitute inequitable conduct. The court reasoned that Landau and Pardo had not understood that the need for an affidavit from a disinterested person might have precluded use of Bullen as an affiant, or that knowledge of Bullen's contact with Bell Canada and its relationship with Lanpar was material to consideration of the disclosures by the PTO.20
The district court also found that neither the Cikra affidavit nor the Rule 116 amendment disclosed that Cikra had worked with the inventors to enable a version of the LANPAR program to operate with another software system, reviewed portions of the LANPAR program source code, and observed the program being used. The district court found that, while this omission in Cikra's affidavit presented a closer question concerning the inventors' intent than the omission in Bullen's affidavit, it still was not clear and convincing evidence of inequitable conduct. The court found that Cikra had had limited contact with the program and that, while prudence would have dictated disclosing Cikra's contact with the invention, the inventors apparently did not know, given their lack of familiarity with patent prosecution, that Cikra's involvement should have been disclosed to the PTO. The district court also found that Cikra's affidavit failed to mention that he had taken a compiler course in college and  had sorting program experience, but that there was no reason for the inventors or their attorney to have believed that such information was relevant to evaluation of his affidavit.21
The Jones affidavit was a different matter. The district court found that neither the Jones affidavit nor the Rule 116 amendment disclosed the following facts:22
(a) Jones worked for Lanpar for not more than eight weeks in January and February 1972, less than six months prior to executing his affidavit.
(b) While at Lanpar and prior to executing his affidavit, Jones learned internal details about the LANPAR Program and acquired an understanding of its concepts.
(c) While at Lanpar and prior to executing his affidavit, Jones received personal instruction from Landau in the internal logic of the LANPAR Program, observed the LANPAR Program in operation, and examined source code listings, flow charts and other written explanatory materials relating to it.
(d) While at Lanpar and prior to executing his affidavit, Jones drafted the text for what became the introduction to what was later produced as the LANPAR Program Logic Manual.
The court found that the information omitted from Jones's affidavit was material to the examiner's evaluation of the affidavit and that the inventors submitted the affidavit with an intent to mislead the PTO. The court found that Landau and Pardo had an opportunity to review Jones's affidavit, as they were sent copies of a draft and the final affidavit after it was executed. In addition, the court found that Pardo was actively involved in providing the attorney with background information regarding the three affiants, particularly Jones. The court found that "Jones's extensive experience with and knowledge of the LANPAR Program contradicted the very essence of the disinterested affidavit" and that the inventors intended to mislead the PTO by omitting that information from Jones's affidavit. The court also found that, since the examiner did not withdraw the rejection in response to Pardo's affidavit, the inventors knew that Jones's connection with the invention would have been material:24
In light of the previous rejection of the Pardo Affidavit as "self serving," Pardo and Landau knew that a reasonable Examiner reviewing the Affidavits would conclude that the affiants were disinterested witnesses with no knowledge of the patent process, particularly where the affiants in great detail presented their education and employment history without any mention of the affiant's connections to the patent applicants or familiarity with the patent invention. Conversely, Pardo and Landau also knew that the PTO Examiner here would, when evaluating the Affidavits, consider it important to know whether the disinterested affiants had prior exposure to the patent process or its commercial Program. (emphasis added).
The court also considered that "the effect of the fraudulent omission in the Jones Affidavit was heightened by the omissions in the other Affidavits." The district court weighed the materiality of the omitted information with evidence of the inventors' intent and concluded that there was clear and convincing evidence of inequitable conduct. Accordingly, the court dismissed Refac's complaint. Refac now appeals.26
Refac argues that the totality of the circumstances precludes an inference of an intent to deceive the PTO. The Jones affidavit contains no affirmative misrepresentations of fact and, according to Refac, it was cumulative of the Cikra and Bullen affidavits and therefore not material. Since Jones had no financial or other interest in Lanpar or the patent application, Refac asserts that the inventors believed him to have been a disinterested party, and that the district court thus erred in its conclusion of inequitable conduct.28
Lotus responds that the district court made proper credibility determinations and exercised sound discretion in its holding. Lotus argues that the inventors' attorney  instructed them to find affiants without a prior involvement with the claimed invention and that the inventors failed to inform the attorney of the affiants' prior knowledge of the LANPAR program. Even if, as Refac claims, the inventors informed the attorney of Jones's prior employment with Lanpar, Lotus argues that the patent should still be unenforceable, as the attorney was under the same duty of disclosure, which was not met.29
A determination of inequitable conduct is committed to the district court's discretion. Accordingly, we review the court's judgment for abuse of discretion. Kingsdown Medical Consultants, Ltd. v. Hollister Inc., 863 F.2d 867, 876, 9 USPQ2d 1384, 1392 (Fed.Cir.1988), cert. denied, 490 U.S. 1067, 109 S.Ct. 2068, 104 L.Ed.2d 633 (1989). To overturn a discretionary ruling of a district court, "the appellant must establish that the ruling is based on clearly erroneous findings of fact or on a misapplication or misinterpretation of applicable law, or evidences a clear error of judgment on the part of the district court." Molins PLC v. Textron, Inc., 48 F.3d 1172, 1178, 33 USPQ2d 1823, 1827 (Fed. Cir.1995).30
Inequitable conduct consists of an "affirmative misrepresentation of a material fact, failure to disclose material information, or submission of false material information, coupled with an intent to deceive." Molins, 48 F.3d at 1178, 33 USPQ2d at 1826 (emphasis added). One alleging inequitable conduct must prove the threshold elements of materiality and intent by clear and convincing evidence. Id., 48 F.3d at 1178-79, 33 USPQ2d at 1826-27. The district court must then weigh the threshold findings of materiality and intent in light of all the circumstances to determine whether they warrant a conclusion that inequitable conduct occurred. Id.; see also Akzo N.V. v. United States Int'l Trade Comm'n, 808 F.2d 1471, 1481-82, 1 USPQ2d 1241, 1247 (Fed.Cir.1986) ("Materiality and intent must also be considered together: the more material the omission or misrepresentation, the less intent that must be shown to reach a conclusion of inequitable conduct."), cert. denied, 482 U.S. 909, 107 S.Ct. 2490, 96 L.Ed.2d 382 (1987). "Information is `material' when there is a substantial likelihood that a reasonable examiner would have considered the information important in deciding whether to allow the application to issue as a patent." Molins, 48 F.3d at 1179, 33 USPQ2d at 1827 (citing In re Jerabek, 789 F.2d 886, 890, 229 USPQ 530, 533 (Fed.Cir. 1986)); see also LaBounty Mfg., Inc. v. United States Int'l Trade Comm'n, 958 F.2d 1066, 1074, 22 USPQ2d 1025, 1031 (Fed.Cir.1992).31
The district court complied with all these requirements. First, it did not clearly err in concluding that the Jones affidavit omitted material information. Jones had worked at Lanpar less than six months before he executed his affidavit, which recited his employment history in such detail that it even included a summer job. Jones had also worked with and reviewed documentation for the commercial embodiment of the invention, the LANPAR program. The district court noted that, although "Jones claims that the opinion he gave in his 1972 Affidavit was not influenced by the knowledge he gained while working at Lanpar," when asked how he prepared his affidavit, Jones testified that he reviewed the application's disclosure and recognized the flow chart as being essentially the same one that Landau had shown him during one of their training sessions in which Landau explained the invention to him. Jones's own testimony thus indicated that he possessed pre-existing knowledge of the invention when he prepared his affidavit. It would surely have been important for the examiner, and any reasonable examiner, to know of Jones's association with Lanpar and his pre-existing knowledge of the LANPAR program. The district court thus did not clearly err in finding this information to have been material.32
The court also did not clearly err in concluding that the totality of circumstances supported an inference of an intent to mislead the PTO. The inventors had an opportunity to review Jones's affidavit before it was submitted to the PTO. Given what the examiner characterized as the self-serving nature of Pardo's affidavit, they were on notice from the PTO that affidavits from disinterested persons were needed in order to overcome the substantive ground of the  rejection. The inventors should therefore have known that the fact of an affiant's prior knowledge of the invention would have been important to the examiner in deciding whether to withdraw the rejection and allow the application, particularly when the examiner had no way of otherwise obtaining the omitted information about Jones's background. See Paragon Podiatry Lab., Inc. v. KLM Lab., Inc., 984 F.2d 1182, 1191, 25 USPQ2d 1561, 1568 (Fed.Cir.1993). "The inference [of an intent to mislead] arises not simply from the materiality of the affidavits, but from the affirmative acts of submitting them, their misleading character, and the inability of the examiner to investigate the facts." Id. (emphasis added).33
Significantly, determining whether there was an intent to mislead the PTO involved credibility determinations. Rhodes, the inventors' attorney, testified that he inquired into Jones's prior association with the inventors and Jones's knowledge of the invention, but that the inventors did not tell him about Jones's previous employment with Lanpar or his knowledge of the LANPAR program. He also testified that, if he had had this knowledge, he would have either disclosed such information to the PTO or not used Jones as an affiant. Pardo, however, testified that his attorney knew that Jones had worked at Lanpar. In the face of this conflicting testimony, the district court determined that Rhodes's testimony was more credible than that of the inventors:34
Landau and Pardo claim they told Rhodes of Jones's employment history with them.
I do not credit this claim. There is no reason for Rhodes to have learned about Jones's prior experience and then accepted the Jones Affidavit. If given this information, the obvious alternative, as Rhodes testified, would have been for him to ask Landau and Pardo to find someone without Jones's experience to submit an Affidavit. Thus, I conclude that Pardo and Landau purposely kept Jones's employment history from Rhodes. (citations omitted).
The district court is best suited to make credibility determinations and we accord such determinations deference. See Fed. R.Civ.P. 52(a); Anderson v. City of Bessemer City, North Carolina, 470 U.S. 564, 575, 105 S.Ct. 1504, 1512, 84 L.Ed.2d 518 (1985) ("When findings are based on determinations regarding the credibility of witnesses, Rule 52(a) demands even greater deference to the trial court's findings; for only the trial judge can be aware of the variations in demeanor and tone of voice that bear so heavily on the listener's understanding of and belief in what is said."); First Interstate Bank of Billings v. United States, 61 F.3d 876, 882 (Fed.Cir. 1995); Molins, 48 F.3d at 1181, 33 USPQ2d at 1829.36
The district court's credibility determination supports an inference of an intent to mislead and it is not clearly erroneous. The court was entitled to conclude that since the inventors did not inform Rhodes of Jones's association with Lanpar and Jones's knowledge of the LANPAR program, even after Rhodes inquired into the backgrounds of the affiants, withholding such information from their attorney and effectively from the PTO was intentional. In view of the examiner's response to Pardo's earlier affidavit, the inventors were on notice that Jones's pre-existing knowledge of the invention would have been important to the examiner's decision whether or not to allow the application and that not disclosing it would increase their likelihood of obtaining a patent. See Paragon, 984 F.2d at 1191, 25 USPQ2d at 1568 ("The natural consequence of [the applicant's] acts was to lead the examiner to believe that the affiants were `disinterested' parties, and the patentees were successful in that effort.").37
In balancing its findings of materiality and intent to arrive at a conclusion of inequitable conduct, the court also took into account its evaluation of the Bullen and Cikra affidavits, which, while not themselves constituting inequitable conduct, heightened the effect of Jones's affidavit. Given the court's thorough evaluation, we cannot conclude that it abused its discretion in deciding that inequitable conduct occurred.38
Refac argues that the Paragon decision "illustrates how far short Lotus' proof fell from establishing conduct so inequitable that  the '249 Patent should be held unenforceable."39
In Paragon, the examiner requested affidavits from a disinterested third party. In response, the applicant submitted to the PTO three affidavits from professionals in the field who attested to the advantages of the invention over the prior art. The affidavits contained the following statement:40
I have not been in the past employed by nor do I intend in the future to become employed by Paragon Podiatry Laboratories, a corporation which I understand is the assignee of the interest in the above captioned patent application.
Paragon, 984 F.2d at 1191, 25 USPQ2d at 1568. They did not disclose that each of them held stock in Paragon, the assignee, and that one or more of them had been a paid consultant. We stated that the representation that the affiants were not employed by Paragon was a "classic example of a half truth" and that the affiants were not "disinterested." Moreover, the "gratuitous averment that each `understood' Paragon was an assignee of the patent also implies they had no connection with their own company." Id. at 1192, 25 USPQ2d at 1569. We concluded that the applicant submitted the affidavits containing a material misrepresentation with the intent to mislead the PTO into granting a patent.42
The rationale of Paragon supports affirmance of the trial court's decision. The fact that the conduct here consists of an omission rather than a misrepresentation does not compel a different result, as either may mislead an examiner. An examiner must be able to evaluate information in an affidavit in context, giving it the proper weight; both the materiality and the inference of intent arising from the omission in Jones's affidavit are enhanced by the otherwise detailed recitation of his employment history. The district court therefore did not abuse its discretion in concluding that the omission of information in Jones's affidavit relating to his status as a disinterested party was intended to mislead the PTO.43
Refac also argues that Jones's affidavit was cumulative to Cikra's and Bullen's affidavits and that it was therefore not material as a matter of law. Refac relies on the following passage in Molins to support its argument: "If the information allegedly withheld is not as pertinent as that considered by the examiner, or is merely cumulative to that considered by the examiner, such information is not material." Molins, 48 F.3d at 1179, 33 USPQ2d at 1827 (citing Scripps Clinic & Research Found v. Genentech, Inc., 927 F.2d 1565, 1582, 18 USPQ2d 1001, 1014-15 (Fed.Cir.1991)).44
Lotus responds that the inventors should not be allowed to shield their inequitable conduct by arguing that the Jones affidavit was not the sole cause for allowance. Lotus states that such a policy would force an inquiry into the decision-making process of the examiner in every case in which inequitable conduct is alleged to have occurred.45
The cited passage from Molins relates to cumulative prior art references, not to cumulative affidavits. Molins cited a discussion in Scripps that also related to cumulative references. "A reference that is simply cumulative to other references does not meet the threshold of materiality that is predicate to a holding of inequitable conduct." Scripps, 927 F.2d at 1582, 18 USPQ2d at 1014-15 (citing Halliburton Co. v. Schlumberger Technology Corp., 925 F.2d 1435, 1440, 17 USPQ2d 1834, 1839 (Fed.Cir.1991)). The facts in Halliburton also involved cumulative prior art references not disclosed to the PTO. Halliburton, 925 F.2d at 1440, 1443, 17 USPQ2d at 1839, 1842. We decline to place submitted cumulative affidavits in the same status as unsubmitted cumulative prior art. While it is not necessary to cite cumulative prior art because it adds nothing to what is already of record (although it may be prudent to do so), one cannot excuse the submission of a misleading affidavit on the ground that it was only cumulative. Affidavits are inherently material, even if only cumulative. The affirmative act of submitting an affidavit must be construed as being intended to be relied upon. It is not comparable to omitting an unnecessary act.46
Whether or not Jones's affidavit was cumulative to that of Cikra's and Bullen's affidavits is also of no consequence. Since  any one of the affidavits from Cikra, Bullen, and Jones may have resulted in an allowance of the claims, each affidavit ipso facto had a certain level of materiality. Cf. Rohm & Haas Co. v. Crystal Chem. Co., 722 F.2d 1556, 1571, 220 USPQ 289, 300 (Fed.Cir.1983) ("In contrast to cases where allegations of fraud are based on the withholding of prior art, there is no room to argue that submission of false affidavits is not material."), cert. denied, 469 U.S. 851, 105 S.Ct. 172, 83 L.Ed.2d 107 (1984). Since the examiner did not allow the claims in response to the inventor's own affidavit, the inventors were on notice that the examiner would consider it important to know of the affiants' pre-existing knowledge of the invention or his connection with the inventors. An inventor cannot submit a misleading affidavit among a plurality of affidavits and later argue that it was the nonmisleading affidavit that resulted in allowance, thus effectively curing the defective affidavit.47
Refac also argues that Jones's affidavit had no probative value and therefore cannot be used to infer an intent to mislead. Refac cites section 716 of the 1972 Manual of Patent Examining Procedure ("MPEP"), which reads as follows:48
The following criteria are applicable to all affidavits or declarations submitted under rule 132:
(2) Affidavits or declarations must set forth facts, not merely conclusions. The facts presented in the affidavits or declarations must be pertinent to the rejection. Otherwise, the affidavits or declarations have no probative value. (citations omitted).
Refac asserts that Jones's affidavit contained only opinion, without the factual statements required by the MPEP guideline for an affidavit to be given probative value, and that it therefore cannot be used to infer an intent to mislead. We do not agree. An affidavit submitted to overcome a rejection is intended to be relied upon. While an affiant may insist that his sworn statements were truthful or that any omissions were not material or not made with intent to deceive, these are matters of proof and credibility, on which the decision here has gone against Refac. But arguing that an affidavit submitted to persuade was defective as presenting only opinion, not fact, and that it should be discounted, qualifies only for a chutzpah award, see Checkpoint Sys., Inc. v. United States Int'l Trade Comm'n, 54 F.3d 756, 763, 35 USPQ2d 1042, 1048 (Fed.Cir.1995), not a reversal. The inventors submitted the Jones affidavit to the PTO in an attempt to overcome a rejection. It was incumbent upon them to provide the PTO with sufficient information for a reasonable examiner to consider the opinion in the affidavit in context, not with a selective and misleading disclosure. The inventors failed to do that and cannot post facto hide behind the MPEP guidelines to argue that what they did with a purpose should be disregarded. See Molins, 48 F.3d at 1182, 33 USPQ2d at 1830 ("Those who are not `up front' with the PTO run the risk that, years later, a fact-finder might conclude that they intended to deceive."); see also Precision Instrument Mfg. Co. v. Automotive Maintenance Mach. Co., 324 U.S. 806, 816, 65 S.Ct. 993, 998, 89 L.Ed. 1381 (1945) (describing the public interest in seeing that patents are not procured through fraud).50
The inequitable conduct found by the district court in this case did not involve what is more commonly (but often unjustifiably) asserted as inequitable conduct, viz., failure to cite relevant prior art or making a material misrepresentation. Holding that the omission of an aspect of one's employment history to be inequitable conduct might thus seem to be unduly severe, a heavy penalty for an arguably minor omission. However, the district court here made findings of materiality and intent to deceive, based partly on credibility findings, and, given our standard of review, we do not consider the findings to be clearly erroneous or the conclusion to be an abuse of discretion. We cannot hold as a  matter of law that omission of a relevant part of one's employment history on an affidavit intended to show the adequacy of the patent specification to one of ordinary skill in the art, when such an affidavit by the inventor was earlier rejected, does not constitute inequitable conduct.51
The district court did not abuse its discretion in holding that the '249 patent is unenforceable on the ground of inequitable conduct.53
 The notice of allowance was later withdrawn following the issuance of the Supreme Court's decision in Gottschalk v. Benson, 409 U.S. 63, 93 S.Ct. 253, 34 L.Ed.2d 273 (1972). The application was then rejected under 35 U.S.C. § 101 for lack of patentable subject matter, which rejection was upheld on appeal to the Board of Appeals. The inventors appealed to the Court of Customs and Patent Appeals and successfully obtained a reversal of the board's decision. In re Pardo, 684 F.2d 912, 214 USPQ 673 (CCPA 1982).55
 The MPEP does not have the force and effect of law; however, it is entitled to judicial notice as the agency's official interpretation of statutes or regulations, provided that it is not in conflict with the statutes or regulations. Molins PLC v. Textron, Inc., 48 F.3d 1172, 1180 n. 10, 33 USPQ2d 1823, 1828 n. 10 (Fed.Cir.1995) (citing Litton Sys., Inc. v. Whirlpool Corp., 728 F.2d 1423, 1439, 221 USPQ 97, 107 (Fed.Cir.1984)).
888 F.2d 878 (1989)2
United States Court of Appeals, District of Columbia Circuit.
Argued September 18, 1989.
Decided October 31, 1989.
A. Sidney Katz, with whom James P. White and Laurie A. Haynie, Chicago, Ill., were on the brief, for appellant.5
Nathan Dodell, Asst. U.S. Atty., with whom Jay B. Stephens, U.S. Atty., John D. Bates, R. Craig Lawrence, Asst. U.S. Attys.,  Dorothy Schrader, General Counsel, and William Roberts, Washington, D.C., Atty., Copyright Office, were on the brief, for appellee.6
Before RUTH BADER GINSBURG, SILBERMAN and D.H. GINSBURG, Circuit Judges.7
Opinion for the Court filed by Circuit Judge RUTH BADER GINSBURG.8
Opinion concurring in the judgment filed by Circuit Judge SILBERMAN.9
By letter dated December 7, 1987, the Copyright Office reported its final action refusing to register a claim to copyright in the video game BREAKOUT, an audiovisual work created in 1975 by Atari, Inc., the predecessor of plaintiff-appellant Atari Games Corporation (Atari). The December 1987 letter, written on behalf of the United States Register of Copyrights (Register), stated that the video game in question "does not contain sufficient original visual or musical authorship to warrant registration." Invoking the judicial review prescriptions of the Administrative Procedure Act, 5 U.S.C. §§ 701-706, Atari unsuccessfully challenged the agency's determination in the district court as "arbitrary, capricious, an abuse of discretion, or otherwise not in accordance with law." 5 U.S.C. § 706(2)(A).11
In this appeal from the district court's entry of summary judgment for the Register, we hold that the Copyright Office did not intelligibly account for its ruling. Because we are unable to determine on the current record whether the Register's action comports with the demand of reasoned decisionmaking, we vacate the district court's judgment and remand the case to that court with instructions to return the matter to the Copyright Office for further consideration consistent with this opinion.12
BREAKOUT, the audiovisual work that is the subject of this dispute, is a coin-operated, ball and paddle video game created in 1975 and successfully marketed by Atari in the following years. BREAKOUT's audiovisual display features a wall formed by red, amber, green, and blue layers of rectangles representing bricks. A player maneuvers a control knob that causes a rectangular-shaped representation of a paddle to hit a square-shaped representation of a ball against the brick wall. When the ball hits a brick, that brick disappears from its row, the player scores points, and a brick on a higher row becomes exposed. A "breakout" occurs when the ball penetrates through all rows of bricks and moves into the space between the wall and the top of the screen; the ball then ricochets in a zig-zag pattern off the sides of the screen and the top layer of the wall, removing bricks upon contact and adding more points to the player's score. Various tones sound as the ball touches different objects or places on the screen. The size of the paddle diminishes and the motion of the ball accelerates as the game is played.14
By letter dated February 5, 1987, Atari sought expedited registration of a copyright claim in the audiovisual work embodied in BREAKOUT. Atari asserted an "urgent need for special handling because of prospective litigation in which [Atari] would be acting as plaintiff." See infra note 3. The Copyright Office responded promptly, but unfavorably. By letter dated February 13, 1987, Copyright Examiner Carmen Martorana declared the work not copyrightable. She reasoned that "[t]o be considered an audiovisual work for registration purposes, the work must contain related pictorial or graphic images, and at  least one of those images must be copyrightable." BREAKOUT did not qualify, she wrote, because neither the "[c]ommon geometric shapes ... contained in th[e] work" nor "the coloring of th[o]se shapes" constituted copyrightable subject matter. Similarly, she stated, "[t]here is not enough original authorship to register a claim in the sounds." She further said that the "images ... created by playing the video game ... are also not registrable since they are created randomly by the player and not by the author of the video game."15
By letter dated May 22, 1987, Shirley B. Wendell of the Examining Division denied reconsideration. She repeated that the common geometric shapes contained in BREAKOUT are not copyrightable, that adding color did not render the work copyrightable, and that "[t]he individual tones or sounds are not copyrightable."16
By letter dated December 7, 1987, Harriet L. Oler, Chief of the Examining Division, denied further reconsideration and announced the agency's final action on the claim. She initially stated that the Register views the work "as a whole" to determine whether registration is warranted. However, to explain her conclusion that BREAKOUT "does not contain sufficient original visual or musical authorship to warrant registration," she separately treated the work's several parts:17
[T]he use of a symbol for a wall drawn in a familiar tile type design is not copyrightable. The same is true of the image of a rectangle used in place of a paddle, a circle [sic] for a ball, and a common four colored stripe embellishing the wall.
The game's sounds, she added, "the three tones used before the ball, and the string of double tones used after it," do not "constitute any copyrightable audio authorship." She further stated that the arrangement of the "stationary screen display" contains no copyrightable authorship because "so few items" appear on the screen and "the arrangement is basically dictated by the functional requirements of this or similar backboard type games." Finally, she noted, Atari was not precluded "from registering a claim in the computer program."19
Atari sought court review of the agency's final action. On cross-motions for summary judgment, the district court concluded that the Register reasonably applied controlling law to the facts before him. Describing the three letters from the Copyright Office as "thoughtful and well-orchestrated" expositions of the "pertinent considerations," the court held that the Register did not abuse his discretion in treating BREAKOUT as one of the "rare" instances of expressive value so slight as to be insufficient for copyright purposes. Atari Games Corp. v. Oman, 693 F.Supp. 1204, 1206, 1207 (D.D.C.1988).20
Section 410 of the Copyright Act, 17 U.S.C. § 410, provides in part:22
(a) When, after examination, the Register of Copyrights determines that, in accordance with the provisions of this title, the material deposited constitutes copyrightable subject matter and that the other legal and formal requirements of this title have been met, the Register shall register the claim and issue to the applicant a certificate of registration under the seal of the Copyright Office....
(b) In any case in which the Register of Copyrights determines that, in accordance with the provisions of this title, the material deposited does not constitute copyrightable subject matter or that the claim is invalid for any other reason, the Register shall refuse registration and shall notify the applicant in writing of the reasons for such refusal.
If registration is refused, the applicant may seek immediate judicial review, as Atari did here, in an action under the Administrative Procedure Act, 5 U.S.C. §§ 701-706. See 17 U.S.C. § 701(d). Alternatively, as noted in the Register's final decision, determination of the copyrightability of the work may be sought in the context of an infringement suit.24
Section 411(a) of the Copyright Act, 17 U.S.C. § 411(a), permits an infringement  suit, despite the Register's refusal to register a copyright claim, if registration submissions to the Copyright Office were in proper form and the Register is notified so that he may exercise a right to intervene. See Nova Stylings, Inc. v. Ladd, 695 F.2d 1179 (9th Cir.1983) (holding mandamus no longer available to compel registration). Registration carries evidentiary weight in an infringement suit. Registration before or within five years after first publication of the work constitutes prima facie evidence of the validity of the copyright; registration after the five-year period may be accorded weight "within the discretion of the court." 17 U.S.C. § 410(c). For Atari, then, registration of a copyright in BREAKOUT might have evidentiary force in an action against an alleged infringer and would assure against the Register's appearance in the infringement action as a party adverse to Atari on the issue of registrability.25
Regarding the district court, our review stance in this case is not deferential:27
Because an award of summary judgment reflects "a determination of law rather than fact," we do not defer to the District Court's conclusions but consider the matter de novo.
Nepera Chem., Inc. v. Sea-Land Serv., Inc., 794 F.2d 688, 699 (D.C.Cir.1986) (quoting Liberty Lobby v. Anderson, 746 F.2d 1563, 1572 (D.C.Cir.1984), vacated on other grounds, 477 U.S. 242, 106 S.Ct. 2505, 91 L.Ed.2d 202 (1986)). We accord due respect, however, to decisions made by the Copyright Office pursuant to authority vested in the Register by Congress. Accordingly, we review the Register's decision under an "abuse of discretion" standard. See John Muller & Co. v. New York Arrows Soccer Team, Inc., 802 F.2d 989, 990 (8th Cir.1986); Norris Indus., Inc. v. International Tel. & Tel. Corp., 696 F.2d 918, 922 (11th Cir.), cert. denied, 464 U.S. 818, 104 S.Ct. 78, 78 L.Ed.2d 89 (1983); Esquire, Inc. v. Ringer, 591 F.2d 796, 806 n. 28 (D.C.Cir.1978), cert. denied, 440 U.S. 908, 99 S.Ct. 1217, 59 L.Ed.2d 456 (1979). For the reasons stated below, we are unable to discern from the final agency action disqualifying BREAKOUT for registration just how the Register is applying the relevant statutory prescriptions. We therefore return the case for the requisite rational explanation. See, e.g., Fort Bragg Ass'n of Educators v. FLRA, 870 F.2d 698, 701 (D.C.Cir.1989); City of Vernon v. FERC, 845 F.2d 1042, 1046-49 (D.C.Cir.1988).29
We initially summarize our concerns; then, to facilitate the Register's further consideration, and guard against rudderless administrative pronouncements, we develop those concerns more fully. See Pacific Northwest Newspaper Guild v. NLRB, 877 F.2d 998, 1003 (D.C.Cir.1989) ("core concern" of court, when petitioned to check against arbitrary and capricious administrative action, is to assure that executive agencies hew to principled "legal theory" and do not indulge in "ad hocery"); Kamargo Corp. v. FERC, 852 F.2d 1392, 1398 (D.C.Cir.1988) (denial of permit is arbitrary and capricious unless the Commission has "acceptable legal support under its authorizing statute"). First, we note the Copyright Act's definition of "audiovisual works" as "a series of related images ... intrinsically intended to be shown by the use of ... devices such as ... electronic equipment, together with accompanying sounds, if any, regardless of the nature of the material objects ... in which the works are embodied." 17 U.S.C. § 101 (definitions). Although the Act uses the phrase "a series of related images," the Copyright Office, even in its final action, emphasized the non-copyrightability of the work's several parts — the wall, paddle, ball, and tones — and also treated "the stationary screen display." See supra p. 880. We are at a loss to understand why the Register did not more solidly link the final decision to the Act's apparent recognition that the whole — the "series of related images"  — may be greater than the sum of its several or stationary parts.30
Second, we do not grasp the standard of creativity the Copyright Office employed in determining whether to register BREAKOUT as an audiovisual work. Was it the normal standard under which a very modest degree of intellectual labor will suffice? See, e.g., West Publishing Co. v. Mead Data Cent., Inc., 799 F.2d 1219, 1223 (8th Cir.1986), cert. denied, 479 U.S. 1070, 107 S.Ct. 962, 93 L.Ed.2d 1010 (1987); 1 M. NIMMER & D. NIMMER, NIMMER ON COPYRIGHT § 1.08[C] (1989). Or did the Office test BREAKOUT against a higher standard, one resembling the "substantial creativity" measuring rod sometimes used to judge derivative works? See 17 U.S.C. § 103; Chamberlin v. Uris Sales Corp., 150 F.2d 512, 513 (2d Cir.1945) (compilations or other derivative works must contain "some substantial, not merely trivial, originality"). And if an elevated creativity requirement was employed, what justified use of a heightened standard?31
Third, the cryptic character of the final agency decision leaves us uncertain whether the action regarding BREAKOUT is consistent with earlier and later pronouncements of the Copyright Office and courts. Put more particularly, we are concerned that the Register may have confused or blended in this case the analytically and operationally separate questions: (1) is a work registrable as one constituting "copyrightable subject matter," see 17 U.S.C. § 410(a), (b); and (2) what is the extent of copyright protection — solid or thin — due a given "original work of authorship." The first question relates to the existence of copyright, the second, to the scope of protection.32
"Copyright protection subsists ... in original works of authorship" including, among several categories of copyrightable subject matter, "audiovisual works." 17 U.S.C. § 102(a)(6). Video games, case law confirms, rank as "audiovisual works" that may qualify for copyright protection. See, e.g., M. Kramer Mfg. Co. v. Andrews, 783 F.2d 421, 436 (4th Cir.1986); Midway Mfg. Co. v. Artic Int'l, Inc., 704 F.2d 1009, 1012 (7th Cir.), cert. denied, 464 U.S. 823, 104 S.Ct. 90, 78 L.Ed.2d 98 (1983); Stern Elecs., Inc. v. Kaufman, 669 F.2d 852, 857 (2d Cir.1982); Midway Mfg. Co. v. Dirkschneider, 543 F.Supp. 466, 479-80 (D.Neb.1981).34
This court and others have defined the word "original" in the Copyright Act's term "original works of authorship," 17 U.S.C. § 102(a), to mean "only that the work `owes its origin to the author' — i.e., that the work is independently created, rather than copied from other works." Reader's Digest Ass'n v. Conservative Digest, Inc., 821 F.2d 800, 806 (D.C.Cir.1987) (quoting Alfred Bell & Co. v. Catalda Fine Arts, Inc., 191 F.2d 99, 102 (2d Cir.1951)). As the district court stated, "[t]here is no dispute in this case, and the Register expressly recognized, that BREAKOUT originated with or was independently created by Atari." Atari Games Corp., 693 F.Supp. at 1205.35
While the Register concedes that BREAKOUT is an independent creation, he concluded that the game is not a "work of authorship" within the meaning of the statute. To constitute a "work of authorship," the material deposited with the Register must pass a "creativity" threshold, i.e., it must embody "some modest amount of intellectual labor." Baltimore Orioles, Inc. v. Major League Baseball Players Ass'n, 805 F.2d 663, 668 n. 6 (7th Cir.1986) (distinguishing the concepts "originality," "creativity," and "novelty," and observing that "[f]or a work to be copyrightable, it must be original and creative, but need not be novel"), cert. denied, 480 U.S. 941, 107 S.Ct. 1593, 94 L.Ed.2d 782 (1987).36
The Register subjected BREAKOUT to a component-by-component analysis, and considered in the aggregate "the stationary screen display." See supra p. 880; see also Brief for Appellee at 11 (arguing that BREAKOUT "does not qualify for copyright because the components of the audiovisual display are not original  works of authorship") (emphasis added). The Act, however, uses the definitional term "series of related images," 17 U.S.C. § 101, and the case law correspondingly indicates that the Register's focus, even if initially concentrated on discrete parts, ultimately should be on the audiovisual work as a whole, i.e., the total sequence of images displayed as the game is played. Stern Elecs., 669 F.2d at 857 ("Assessing the entire effect of the [video] game [SCRAMBLE] as it appears and sounds, we conclude that its repetitive sequence of images is copyrightable as an audiovisual display."); see also 113 CONG. REC. 8587-88 (1967) (Congressman Poff) ("A series of related images includes any group of two or more images having some type of relationship in their subject matter which gives unity to the group as a whole. However, the fact that some or all of the individual images in the group would also constitute separate works does not prevent the group of images from being an audiovisual work.").38
In the clarification forthcoming on reconsideration by the Copyright Office, we anticipate that the Register will take careful account of our recent opinion in Reader's Digest, 821 F.2d at 806, in which we observed:39
None of the individual elements of the Reader's Digest cover — ordinary lines, typefaces, and colors — qualifies for copyright protection. But the distinctive arrangement and layout of those elements is entitled to protection as a graphic work.... Reader's Digest has combined and arranged common forms to create a unique graphic design and layout. This design is entitled to protection under the Copyright Act as a graphic work.
See also Apple Barrel Prods., Inc. v. Beard, 730 F.2d 384, 388 (5th Cir.1984) (component parts "neither original to the plaintiff nor copyrightable" may, in combination, create a "separate entity [that] is both original and copyrightable"); Roth Greeting Cards v. United Card Co., 429 F.2d 1106, 1109 (9th Cir.1970) (greeting cards held to be copyrightable although textual matter standing alone was not copyrightable; "all elements of each card, including text, art work, and association between art work and text, [must] be considered as a whole").41
The level of creativity necessary and sufficient for copyrightability has been described as "very slight," "minimal," "modest." See, e.g., West Publishing Co., 799 F.2d at 1223; Thomas Wilson & Co. v. Irving J. Dorfman Co., 433 F.2d 409, 411 (2d Cir.1970), cert. denied, 401 U.S. 977, 91 S.Ct. 1200, 28 L.Ed.2d 326 (1971); 1 M. NIMMER & D. NIMMER, NIMMER ON COPYRIGHT §§ 1.08[C], 2.01[B] (1989). In defense of the judgment that BREAKOUT does not pass the "modest" creativity threshold, appellate counsel for the Register pointed to the Copyright Office regulation providing that "familiar symbols or designs" and "mere variations of typographic ornamentation, lettering or coloring" are not subject to copyright. 37 C.F.R. § 202.1. Again, we are concerned that the Register's attention may have trained dominantly on components, not on the work as a whole — the full "series of related images." 17 U.S.C. § 101 (defining "audiovisual works"); see supra pp. 879-80, 882-83.43
Furthermore, we note that simple shapes, when selected or combined in a distinctive manner indicating some ingenuity, have been accorded copyright protection both by the Register and in court. See, e.g., Soptra Fabrics Corp. v. Stafford Knitting Mills, Inc., 490 F.2d 1092, 1094 (2d Cir.1974) (concluding that fabric design consisting of strip of crescents with scalloping or ribbons and rows of semicircles "constitutes modest but sufficient originality so as to support the copyright"); Tennessee Fabricating Co. v. Moultrie Mfg. Co., 421 F.2d 279, 282 (5th Cir.) (holding that filigree pattern of intercepting  straight and arc lines "possessed at least the minimal degree of creativity required for a copyright"), cert. denied, 398 U.S. 928, 90 S.Ct. 1819, 26 L.Ed.2d 91 (1970); Concord Fabrics, Inc. v. Marcus Bros. Textile Corp., 409 F.2d 1315, 1316 (2d Cir.1969) (treating as subject to copyright protection fabric design consisting of a circle within a square within a circle); In Design v. Lynch Knitting Mills, Inc., 689 F.Supp. 176, 178-79 (S.D.N.Y.) (upholding copyright of rhomboid pattern on a sweater), aff'd, 863 F.2d 45 (2d Cir.1988). We are thus uncertain whether or how the Register's decision on BREAKOUT harmonizes with prior Copyright Office actions and court rulings on the creativity threshold.44
In its brief on appeal, the Copyright Office compared Atari's claim for protection of its work "as a whole," to the protection copyright law affords to compilations and other derivative works. Brief for Appellee at 14. Derivative works, several decisions state, to be copyrightable, must meet a test of "substantial," not merely "minimal," creativity. See, e.g., Past Pluto Prods. Corp. v. Dana, 627 F.Supp. 1435, 1441 (S.D.N.Y.1986). To our knowledge, however, neither the Copyright Office nor any court has ranked as "derivative" a video game that, like the BREAKOUT game Atari produced in 1975, is not based on prior models. Cf. M. Kramer Mfg. Co., 783 F.2d at 428 (request for registration as a derivative work of video game building on prior models).45
We recall here the suggestion initially made by the Copyright Office that BREAKOUT's images are created "by the player and not by the author of the video game." See supra pp. 879-80. We are mindful, however, of the cogent exposition of our sister circuit regarding another video game:46
Although there is player interaction with the machine during the play mode which causes the audiovisual presentation to change in some respects from one game to the next in response to the player's varying participation, there is always a repetitive sequence of a substantial portion of the sights and sounds of the game, and many aspects of the display remain constant from game to game regardless of how the player operates the controls.
Williams Elecs., Inc. v. Artic Int'l, Inc., 685 F.2d 870, 874 (3d Cir.1982); accord Midway Mfg. Co., 704 F.2d at 1012 ("The player of a video game does not have control over the sequence of images that appears on the video game screen.... The most he can do is choose one of the limited number of sequences the game allows him to choose.").48
Copyright protection extends only to "expression," not to "ideas." 17 U.S.C. § 102(b); Mazer v. Stein, 347 U.S. 201, 217, 74 S.Ct. 460, 470, 98 L.Ed. 630 (1954). The Register sees the two as merged in the  BREAKOUT game. BREAKOUT contains no expression, he maintains, separable from the game itself, and therefore does not qualify as copyrightable subject matter. Eleven months prior to the final agency action in this case, the Fourth Circuit declared "untenable" lump categorization of video games as "idea" rather than "expression." M. Kramer Mfg. Co., 783 F.2d at 436-37.50
The Fourth Circuit, in M. Kramer Mfg. Co., acknowledged and distinguished precedent holding that when the subject matter allows for only a very limited manner of expression, the idea and its expression remain a unit, so that there is no copyrightable material. Morrissey v. Procter & Gamble, 379 F.2d 675, 678-79 (1st Cir.1967) (copyright does not extend to rules for "sweepstakes" type sales promotion contest). But works in the computer's domain generally have not fit that bill, the M. Kramer Mfg. Co. panel observed. Instead, the variety of ways to perform the same function sustains the classification of such works as "expression." M. Kramer Mfg. Co., 783 F.2d at 436 (quoting Apple Computer, Inc. v. Franklin Computer Corp., 714 F.2d 1240, 1253 (3d Cir.), cert. denied, 464 U.S. 1033, 104 S.Ct. 690, 79 L.Ed.2d 158 (1984)). Compare Herbert Rosenthal Jewelry Corp. v. Kalpakian, 446 F.2d 738, 742 (9th Cir.1971) (rejecting infringement of registered copyright claim brought by manufacturer of jeweled pin in the shape of a bee; court held that idea of pin and its expression were inseparable, defendants were therefore free to copy the idea and, consequently, to produce a jeweled bee pin that looked like plaintiff's) with Atari, Inc. v. Amusement World, Inc., 547 F.Supp. 222, 227 (D.Md.1981) (observing that "the idea of a video game involving asteroids is a much more general idea than the rather specific concept of a jewelled pin in the shape of a bee, and the former is capable of many forms of expression," i.e., differently designed and combined symbols, movements, and sounds). But cf. Stern Elecs., 669 F.2d at 857 (leaving open the issue whether "a sequence of images ... might contain so little in the way of particularized form of expression as to be only an abstract idea portrayed in noncopyrightable form").51
In this light, we do not follow the Register's thought in describing BREAKOUT's arrangement as dictated by "functional requirements." See supra p. 880. Atari demonstrated that a large variety of "arrangements" or designs might have been devised in lieu of those featured in BREAKOUT, i.e., in place of the objects represented (multi-colored brick wall, square ball, and shrinkable rectangular paddle), the sounds employed (their tones and duration), and the speed and artificial direction of the ball's movement. See Addendum to Reply Brief for Appellant; Williams Elecs., Inc. v. Bally Mfg. Corp., 568 F.Supp. 1274, 1281 (N.D.Ill.1983) (observing that, unlike an arcade pinball game, the audiovisual aspects of a video game "are conceptually separable from its utilitarian aspects"); Patry, Electronic Audiovisual Games: Navigating the Maze of Copyright, 31 J. COPR. SOC'Y 1, 46 (1983) ("[E]ven the simplest game may have variations of sizes, shapes, sequences, colors and sounds.")52
Nor can it convincingly be maintained that audiovisual display and computer program are so linked that it is necessary or sufficient for Atari to register a claim in the computer program. Cf. supra p. 880. Registering a claim in the program  would not securely protect "the series of related images," 17 U.S.C. § 101, for which Atari seeks an "original work of authorship" copyright seal. "[M]any different computer programs can produce the same `results,' whether those results are an analysis of financial records or a sequence of images and sounds." Stern Elecs., 669 F.2d at 855. "[W]riting a new program to replicate the play of [a video game] requires a sophisticated effort, but it is a manageable task." Id.; see Patry, 31 J. COPR. SOC'Y at 5 ("A knock-off manufacturer could ... write a computer program which would exactly replicate the audiovisual display but which would not replicate the underlying computer program. In such an event, the registration of the computer program ... would be ineffective since it is the audiovisual display which is sought to be protected.").53
Even if BREAKOUT contains "expression," the Register additionally suggests, the symbols displayed are so ordinary and commonplace as to fail under scenes a faire analysis. The term scenes a faire refers to stereotyped expressions, "incidents, characters or settings which are as a practical matter indispensable, or at least standard, in the treatment of a given topic." Alexander v. Haley, 460 F.Supp. 40, 45 (S.D.N.Y.1978). In Atari, Inc. v. North Am. Phillips Consumer Elecs. Corp., 672 F.2d 607 (7th Cir.), cert. denied, 459 U.S. 880, 103 S.Ct. 176, 74 L.Ed.2d 145 (1982), the court placed "[c]ertain expressive matter" in the video game PAC-MAN in a scenes a faire compartment. 672 F.2d at 616-17. But the panel in that case ultimately did not conclude that the expressions it treated as scenes a faire gained no copyright protection. Instead, the panel said that the items in question (maze, scoring table, tunnel exits, dots) should "receive protection only from virtually identical copying." Id. at 617. That statement indicates that "the scenes a faire doctrine limits only the scope of a given material's protection, not its copyrightability." Nash v. CBS, Inc., 691 F.Supp. 140, 144 (N.D.Ill.1988).54
We are unable to detect from the final decision before us the standard the Register is using to differentiate material that cannot constitute copyrightable subject matter and therefore should not be registered, from material that may be copyrightable, although perhaps meriting only "thin" protection when the character of its "expression" is tested in an infringement suit. Cf. Continental Cas. Co. v. Beardsley, 253 F.2d 702, 704 (2d Cir.) (distinguishing between the existence of copyright and its scope), cert. denied, 358 U.S. 816, 79 S.Ct. 25, 3 L.Ed.2d 58 (1958). Because neither the idea/expression dichotomy nor the scenes a faire doctrine, under the prevailing case law, reveals to us why BREAKOUT should rank as a work in which no copyright can exist, we are currently unable to approve the Register's decision under those rubrics.55
For the reasons stated, we reverse the summary judgment entered by the district court. We remand this case to that court with instructions to return the matter of Atari's application to the Register for renewed consideration consistent with this opinion.57
It is so ordered.58
We are asked in this case to review the decision of the Register of Copyrights denying Atari's application for a registration in the audio-visual display accompanying its game BREAKOUT. The copyrightability of the display is an issue currently before the District Court for the Northern District of Illinois where Atari has brought  an action against a putative infringer. See Atari Games Corp. v. Romstar, Inc., Civil No. 87 C 9504. Because a registration would afford something of an evidentiary advantage in that suit, see infra at 879-880, Atari has chosen to pursue this petition for review simultaneously with the infringement suit.60
I join the judgment of the court — remanding the case to the Register of Copyrights for adequate explanation — because I cannot determine confidently from the Register's December 7, 1987 letter, the final agency action, what standard the Office used to deny registration. I write separately because I think the majority opinion could be misinterpreted so as to confine improperly the Register's discretion on remand.61
We must bear in mind that when we review the Register's determination to accept or reject an application for registration, we do not make a final decision on the copyrightability of the item. In fact, as the majority opinion recognizes, the Copyright Office's imprimatur is worth only a rebuttable presumption as to copyrightability in an infringement action. And as the government points out, the Copyright Office receives over a 100,000 applications every year. Every time the Register denies registration for too little creativity it cannot be expected to issue an opinion that compares with the learned offerings of my colleagues. I think that is why the courts have generally thought abuse of discretion to be the appropriate standard to review the Office's denial of a registration. Since the applicant can gain full judicial review of copyrightability in an infringement action, the costs of forcing too fine an analysis and too extensive an explanation of a denial of registration are not worth the benefits — particularly when reviewing a question which has unavoidably subjective aspects such as how much creativity is sufficient to force the Copyright Office to register a proffered work.62
If, however, the Register wishes to make a categorical distinction between classes of works such as video games as compared to other offerings such as works of art, and that distinction is to be based on the Register's interpretation of the Copyright Act — which distinguishes between "idea" and "expression" — his determination might even be subject to a somewhat stricter scope of review than abuse of discretion — but it would still be quite deferential. I refer, of course, to Chevron, which obliges us ordinarily to leave undisturbed a permissible or reasonable agency interpretation of a statute if Congress has not directly addressed the issue presented. See Chevron U.S.A. Inc. v. NRDC, 467 U.S. 837, 104 S.Ct. 2778, 81 L.Ed.2d 694 (1984). If the Register has adopted such an interpretation to govern his office's decisions on registration, that does not mean that the judiciary would be obliged to afford deference to that position in an infringement action, which, of course, is not a direct review of agency action governed by the Administrative Procedure Act. The Copyright Act is quite explicit as to the weight a registration decision is to be given in that kind of judicial proceeding. The Register's decision to grant a copyright merely constitutes prima facie evidence of the copyright's validity in any infringement action brought within five years of the works first publication (and only whatever weight the court deems appropriate for actions brought after that time), see 17 U.S.C. § 410(c); judicial review of questions of law, including the question of copyrightability, is otherwise entirely de novo. See Durham Industries, Inc. v. Tomy Corp., 630 F.2d 905, 908 (2d Cir.1980).63
It is unclear to me whether the Register has drawn a categorical distinction between idea and expression in this case. It was  suggested at oral argument that if a still of any of the computer images that appear during the game of BREAKOUT were submitted to the Copyright Office as a work of art, a copyright would issue. In that form, perhaps, the Register would not dispute the presentation's creativity. But the Register is apparently more willing to reject video game displays as insufficiently creative and has done so, not only in the case of BREAKOUT, but also in several other instances that were brought to the court's attention. It would seem then, that the Copyright Office is using a different standard to determine the copyrightability of video games than it uses for other works — which it may well be entitled to do — but it has not explained what those standards are (if they are indeed different) nor how it applies them.64
The only indication we have of how the Register justifies this divergent treatment is the statement in the December 7 letter referring to the arrangement of the few items on the screen (at any given moment) as "basically dictated by the functional requirements of this or similar backboard type games." The letter does not further explain what the Copyright Office means by that cryptic statement, but, in its brief, the government argues that "BREAKOUT represents no more than a videogame idea" and therefore is not protected under the copyright statute. See 17 U.S.C. § 102. The government's brief further states that "games have been particularly susceptible to copying under copyright because the core feature — the idea for the game — cannot be protected." The government thus seems to be suggesting — although it is by no means clear, even in its brief — that in distinguishing between unprotected ideas and protected expressions under the copyright statute (an obviously difficult analytical task) the Register adopts a somewhat different approach for games than it does for, let us say, a magazine cover. Cf. Reader's Digest Ass'n v. Conservative Digest, Inc., 821 F.2d 800 (D.C.Cir.1987).65
I have the impression from the letter and brief that what underlies the Register's position is the notion that works of art — for instance, a drawing of the Potomac River or even of simple geometrical shapes — are almost entirely "expression"; the "idea" element is insignificant, and the Register therefore, seems more readily to afford them registration. On the other hand, the Register apparently believes that a video game's fundamental character is its idea or concept, and the form of expression it takes may be less important. The geometric shapes that appear at any moment on the BREAKOUT screen, and the rather simple audio tones, under that approach, would be seen primarily as a function of the idea of the game rather than an independent attempt at expression. If this is what accounts for the Register's disparate treatment of video displays and works of art, it may or may not be a "permissible interpretation" of the Copyright Act by the Register of Copyrights. See Chevron U.S.A. Inc. v. NRDC, 467 U.S. 837, 104 S.Ct. 2778, 81 L.Ed.2d 694 (1984). I cannot be confident that this is even the Register's view since it is only hinted at in the Register's letter and only marginally elaborated in the government's brief. For that reason, I believe the case should be remanded to the Copyright Office for adequate explanation of its decision, and therefore I join in the judgment of the court.66
The primary problem I find in the majority's opinion is its implicit, if not explicit, expansion of the scope of our review of the Copyright Office's registration decisions. To be sure, the majority nominally accepts abuse of discretion as the proper standard — surely the most deferential form of judicial review of agency action that we can employ. But as far as I can determine, there is no connection between the majority's adoption of that standard and its further discussion of the issues in the case. The majority's holding, set forth at pages 881-882, is that the Register's explanation of his action was inadequate to afford judicial review. The majority has three questions as to the Register's letter: (a) did the Register treat the work as a whole or only its components? (b) did the Register employ the "normal" standard of creativity? and (c) is the Register's decision consistent with earlier and later pronouncements  of the Copyright Office and courts? I agree, as I have already indicated, that the Register is quite unclear as to the standard of creativity he is applying, particularly whether he is employing a different standard for video games, and therefore I have no fundamental quarrel with the majority's decision to remand for further explanation on that point. But see infra at 890. But the majority's other concerns, though also phrased in terms of questions, seem to be points of disagreement rather than confusion. For instance, the majority's statement "we are at a loss to understand why the Register did not more solidly link the final decision to the Act's apparent recognition that the whole — the `series of related images' — may be greater than the sum of its several or stationary parts," Maj.Op. at 881 (emphasis added), reflects a difference in emphasis, not judicial concern with agency inarticulateness. And when the majority says that it is "uncertain" whether the Register's decision is "consistent with earlier and later pronouncements of the Copyright Office and courts," Maj. Op. at 882 (emphasis added), it is implying, not an inability to understand the Register, but rather that the Register's position is vulnerable if it departs from some judicial interpretations — which sounds like at least a tentative view on the merits. Of course even a suggestion that the Register is barred from adopting an interpretation of the Copyright Act regarding video games that is inconsistent with the view expressed by certain courts (let alone some scholarly commentators) would be at odds with the abuse of discretion standard of review; it would more nearly resemble de novo scrutiny. If that is what the majority means to imply, it is, in my view, not good administrative law. Thereafter, the majority launches into a thoughtful discussion of copyright law which — whatever value it may have to copyright law aficionados — does not seem to relate directly to the narrow issue before us now and therefore could be misinterpreted.67
In that regard, I find the majority's discussion of the Fourth Circuit's opinion about the application of the idea/expression distinction to video games expressed in M. Kramer Mfg. Co. v. Andrews, 783 F.2d 421 (4th Cir.1986), a copyright infringement case (not cited by the parties), to be somewhat misleading, surely premature, and perhaps inapposite. There, the court of appeals rejected a district court suggestion that video games are never copyrightable. Although the court recognized that "it is sometimes difficult to distinguish between the two concepts of `idea' and `expression,'" and that "if there is only one way to express the idea, `idea' and `expression' merge and there is no copyrightable material," see id. at 436, it seemed to regard computer games as more expression than idea and therefore readily copyrightable. The Fourth Circuit was not, however, reviewing a determination made by the Register of Copyrights. It may well be that if this issue came to us as it did to the Fourth Circuit in Kramer, as an infringement action in which the court was not obliged to defer to an agency's action or interpretation, I would follow the Fourth Circuit's approach, but that hardly justifies a preemptive rejection of any other practice the Register may adopt. That the Fourth Circuit thought "`untenable'" the categorization of the video game before it as "`idea'" rather than "`expression'" Maj.Op. at 884-885 (quoting Kramer, 783 F.2d at 436), does not necessarily preclude the Register from distinguishing video games from other submitted works on idea versus expression grounds. I believe that the proper course in the review of a registration decision is to allow the Register to present his interpretation of the idea/expression dichotomy — which he has not done clearly here, even in counsel's post hoc suggestions — before the court offers its own guidance.68
Similarly, I find the court's discussion of the Register's "component-by-component analysis" of BREAKOUT to be a bit heavy-handed.  In the December 7 letter, summarized fairly in the majority opinion, the Register denied registration because the pictorial and audio components of the game were too simple to pass the nontrivial test for creativity of authorship. I doubt there is any better way to say something is too simple than merely to assert it. When the Register tried to explain why it thought the pictorial and audio aspects of the game were insufficiently creative, it broke the game down into its components and analyzed each part. That leads the majority to conclude that the Office did not judge the work as a whole and therefore, the majority seems to imply, the Office ran afoul of the Copyright Act as interpreted by various courts of appeals. See Maj.Op. at 882 (quoting 17 U.S.C. § 101 which defines audio-visual displays as a "series of related images"); see also Maj.Op. at 883. The December 7 letter, however, asserts that the Register did judge the work as a whole. I do not think the Register can be faulted for analyzing each component of the work. In explaining how one determined the copyrightability vel non of an audio-visual display, it seems that one would inevitably discuss the components.69
In much the same way, the majority appears to prescribe the proper standard of creativity that the Register should employ in assessing audio-visual displays. See Maj. Op. at 883-84. I agree, as I have said, that the Register was unclear as to what standard of creativity should be applied. But I do not think that the Register should be bound on remand to accept the creativity standard found to be "normal" or appropriate by certain courts of appeals and by Professor Nimmer. See Maj. Op. at 881-82. If the Register believes that video games should have to meet a "substantial" rather than a "minimal" creativity threshold, and he adequately explains that interpretation, we would properly review the Register's decision by applying a reasonableness standard or an abuse of discretion standard, not by deciding merely whether it was consistent with the rulings of courts and the analysis of scholars.70
* * *71
I agree with the majority that we properly remand here because, in my view, the Register has not explained if or why it is employing a categorical distinction between the registrability thresholds for video game displays and other works. But we must be careful when we choose this procedural option not to make it a device to induce an agency to provide the explanation and the result we think correct. If improperly read, the majority opinion might have the effect of causing the Copyright Office to register virtually any offering. So far as I can determine, no court since 1941 has reversed a decision by the Register to deny an initial application for a copyright. And it may well be that, as a practical matter, only denials are vulnerable to legal challenge. If that is so, we should not create incentives to register, the effect of which we do not understand.72
 See 17 U.S.C. § 701(d) (specifying that most actions taken by the Register of Copyrights are subject to the provisions of the Administrative Procedure Act).73
 Copyrights registered in June 1983 in the home version of BREAKOUT and in the arcade game SUPER BREAKOUT were not timely brought to the attention of the district court and form no part of the record before this court. See Atari Games v. Oman, No. 88-0021 (D.D.C. Aug. 18, 1988) (memorandum order denying motion for reconsideration).74
 Atari has instituted suit against an alleged infringer. Atari Games Corp. v. Romstar, No. 87 C 9504 (N.D.Ill.).75
 On brief, the Register correctly commented that Reader's Digest should not be read to hold that "anything submitted to the Copyright Office for registration which contains more than one figure or object would be per se copyrightable." Brief for Appellee at 15. The court in that case spoke of a "distinctive arrangement," one that "create[s] a unique graphic design."76
 After oral argument, in response to the court's inquiry, the Copyright Office identified three instances, in addition to BREAKOUT, in which registration as an audiovisual work was denied to a video game: TIC TAC TOE (registration rejected Aug. 30, 1989), OCTASY (registration rejected Oct. 21, 1988), and DRAW POWER DOUBLE DOWN (registration originally rejected Aug. 26, 1983, final rejection after appeal, Aug. 12, 1989). Notice to the Court of Other Videogame Rejections by the United States Copyright Office (Sept. 27, 1989). Before this post-argument submission, the Copyright Office had not drawn the court's attention to any instance, other than BREAKOUT, of the Register's refusal to register a video game as an audiovisual work. The court cannot discern from the Notice whether the three audiovisual works now specified by the Copyright Office are comparable to BREAKOUT. Nor do we know why the screen displays in these cases were found to lack sufficient authorship. For example, we are not informed whether any of these submissions were derivative works based on prior models.77
 It now appears settled that video games can qualify as works "fixed in [a] tangible medium of expression." 17 U.S.C. § 102(a); see M. Kramer Mfg. Co. v. Andrews, 783 F.2d 421, 440-42 (4th Cir.1986); Stern Elecs., Inc. v. Kaufman, 669 F.2d 852, 855-56 (2d Cir.1982); A. LATMAN. R. GORMAN & J. GINSBURG, COPYRIGHT FOR THE NINETIES 87-88 (3d ed. 1989). But cf. Stern Elecs., 669 F.2d at 857 (recognizing that there might be repeating sequences so simple and invariable, or insubstantial a part of the whole that copyrighting would not be warranted).78
 But cf. NEC Corp. v. Intel Corp., 10 U.S.P.Q.2d 1177, 1179, 1989 WL 67434 (N.D.Cal.1989):79
[A]s a matter of practicality, the issue of a limited number of ways to express an idea is relevant to infringement, but should not be the basis for denying the initial copyright. The Register of Copyrights will not know about the presence or absence of constraints that limit ways to express an idea. The burden of showing such constraints should be left to the alleged infringer. Accordingly, in the absence of Ninth Circuit authority to the contrary, it is concluded that the relationship between "idea" and "expression" will not be considered on the issue of copyrightability, but will be deferred to the discussion of infringement.
 Written computer programs are copyrightable as literary works. See 1 M. NIMMER & D. NIMMER, NIMMER ON COPYRIGHT § 2.04[C] (1989).81
 At oral argument a suggestion was made that games are categorically accorded distinctive treatment by the Register. But cf. Patry, Electronic Audiovisual Games: Navigating the Maze of Copyright, 31 J. COPR. SOC'Y 1, 56 (1983) ("It is true that electronic audiovisual games are `games,' yet ... no matter how humble in originality, such games are still a protectible form of expression."). The final decision we are reviewing, however, did not say if or why games, as a category, are different, so we do not address that prospect.82
 The Register typically gives no explanation when the Office registers an offering; the Act requires an explanation if the Office denies registration. See 17 U.S.C. § 410(c).83
 17 U.S.C. § 102(b) provides that:84
In no case does copyright protection for an original work of authorship extend to any idea, procedure, process, system, method of operation, concept, principle, or discovery, regardless of the form in which it is described, explained, illustrated, or embodied in such work. (emphasis added).
 It is not clear what the majority means by earlier and later "pronouncements" of the Copyright Office.86
 The Register is not necessarily bound by its previous decisions — subsequently upheld by various courts in infringement actions — granting copyrights to a number of fabric designs and a room divider consisting of simple geometric shapes. See Maj.Op. at 883-84. Since the Copyright Office is only required to explain why it rejects but not why it grants an application for a copyright, see 17 U.S.C. § 410(c), none of those decisions indicates why the Register decided to copyright those works or that the Register has interpreted the Copyright Act to demand a "minimal" creativity standard for registrability to be applied across the board to all submissions.87
 See Bouve v. Twentieth Century-Fox Film Corp., 122 F.2d 51 (D.C.Cir.1941). But at that time, the registration of copyrights was considered "a ministerial duty imposed upon him by the law...." Id. at 56.88
 Putative challengers to the grant of registration — such as the defendant in the currently pending infringement suit that apparently precipitated this unusual petition for review of a Copyright Office's registration decision — may not know of the Copyright Office's action in time to bring a suit under the Administrative Procedure Act. If, on the other hand, they do typically know in time, we may find more and more litigation shifting from infringement actions to challenges of registration decisions — which does not seem desirable.
(a) Making of Additional Copy or Adaptation by Owner of Copy.— Notwithstanding the provisions of section 106, it is not an infringement for the owner of a copy of a computer program to make or authorize the making of another copy or adaptation of that computer program provided:2