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XIV. Causation

Original Creator: Jonathan Zittrain Current Version: Samantha Bates Show/Hide

There’s no tort of “attempted negligence.” In order for ultimate liability to accrue, a defendant must not only breach a duty owed to a harmed plaintiff, but that breach must be the cause-in-fact of the harm. Someone speeding through the pedestrian stop light in Harvard Square isn’t held responsible for harm done a few minutes later when a carefully-driven car just so happens to independently get into an accident with a pedestrian, even though it was mere fortuity that the earlier careless driver didn’t hurt anyone.

If I carelessly spill oil on the floor and wander away, and you slip on it as you turn the corner, causation is pretty clear. But what if you were running so quickly over the area that I can show you would have taken a spill irrespective of the oil? That’s not so easy to prove, but in theory it could defeat causation, just as a negligently-maintained dam collapsing in a big storm could be thought of as mere “accident” if the storm were so large that even a well-maintained dam would have buckled. Causation can be tricky to prove in other contexts, such as establishing that a particular chemical causes cancer. To what level of certainty must a causal link be determined? Again, the usual standard is “more likely than not,” but other formulations might better capture the moral instinct that requires proving causation, and even small changes in phrasing can affect a jury’s deliberations.

Once we understand that causation is a required element, there are still questions about what exactly it means to say that X caused Y. Should the presence of other causes matter? One common formulation, good enough for most purposes, is “but-for” causation: without the defendant’s negligence, the harm would not have arisen. But what happens when there are two negligent parties, with each party’s act sufficient to cause the harm? Can each point the finger at the other, since one alone is sufficient to have harmed, and therefore neither is a “but for” cause? Not to bury the lede: the answer there tends to be “no”; we can’t allow a surfeit of negligence across multiple parties to perversely result in no liability. When else might “but-for” causation be loosened?

When there is more wrongdoing than there is harm to go around, the law runs into the issue of how to allocate liability among defendants. One simple route is “joint and several liability,” where each wrongdoer can be found liable for up to 100% of the harm, and the plaintiff may elect from whom to collect what, so long as no overcollection takes place. Should this be the rule, for example, when intentional and negligent acts combine, such as an assailant hurting someone thanks to a hotel’s negligently-maintained lock?


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    1. 1.1 Show/Hide More Howard v. Wal-mart Stores, Inc.--"The 'More-Likely-Than-Not' Standard for Causation"
      Original Creator: Jonathan Zittrain Current Version: Samantha Bates
      Should courts hold that a defendant cannot be proved to “cause” the harm, if the evidence merely supports that it was “more likely than not” that the defendant caused the harm?
      Plaintiff slipped and fell in a puddle of liquid soap on the floor of a Wal-mart store. The plaintiff sued Wal-mart for negligence; however, the evidence&#8212;at best&#8212;could only support an inference that it was <em>more likely than not</em> that a Wal-mart employee is to blame for the spill. Nevertheless, the jury returned a verdict for the plaintiff.
    2. 1.2 Show/Hide More Stubbs v. City of Rochester--"The Sewage in the Drinking Water Case"
      Original Creator: Jonathan Zittrain Current Version: Samantha Bates
      When there are multiple possible causes of the plaintiff’s harm—only some of which the defendant is responsible for—should the plaintiff be required to disprove all other possible causes in order to prevail?
      For several months, the defendant waterworks failed to keep sewage-infested water from mingling with the city’s potable water. During this period, the plaintiff drank contaminated tap water and contracted typhoid fever. The plaintiff sued the city on the theory that the polluted water was the cause of his illness. However, typhoid fever was known to have at least eight different causes, many of which are independent from contaminated drinking water. At trial, the plaintiff produced much evidence that supported contaminated drinking water as the likely cause of his affliction. However, he does not provide evidence which eliminates all the other possible causes.
    3. 1.3 Show/Hide More Anderson v. Minneapolis, St. P. & S. St. M. R.R. Co.--"The Multiple Fires Case"
      Original Creator: Jonathan Zittrain Current Version: Samantha Bates
      Should courts regard a defendant’s conduct as a liable cause of the plaintiff’s harm if the harm would have occurred irrespective of the defendant’s conduct?
      The plaintiff alleged that defendant’s locomotive started a fire which eventually spread and destroyed some of the plaintiff’s property. However, the defendant contended that the damage was caused by nearby, independent fires of unknown origin. At trial, it was unclear if the plaintiff’s property was damaged by the fire caused by the defendant, the independent fires of unknown origin, or some combination of the two.
    4. 1.4 Show/Hide More Brown v. Wal-Mart--"The Phantom Tortfeasor"
      Original Creator: Jonathan Zittrain Current Version: Samantha Bates
      Should a defendant’s liability be excused if the action of an unknown intervening party seems to be a more substantial cause of the plaintiff’s injury?
      Plaintiff is a young boy who slipped on ice and water in the vestibule of defendant’s store. The evidence suggested that another customer had caused the spill; however, defendant was unable to provide any evidence identifying a specific customer. There is also evidence that the defendant’s business practice created a distinct possibility of customers spilling drinks in the entrance-ways of the store.
    1. 2.1 Show/Hide More Summers v. Tice--"The Simultaneously Negligent Shooters"
      Original Creator: Jonathan Zittrain Current Version: Samantha Bates
      If several defendants act negligently and one among them must have caused the harm, but the plaintiff is unable to prove which defendant did so, should courts hold the defendants liable?
      Plaintiff goes out hunting with the two defendants. After plaintiff flushed a quail out of hiding, both defendants shot at the quail, in the plaintiff’s direction, despite being aware of the bird’s proximity to the plaintiff. Plaintiff was struck in the eye and lip with shotgun pellets. At trial, it was not possible to link the wounding pellets to a particular gun.
    2. 2.2 Show/Hide More Garcia v. Joseph Vince Co.--"Two Manufacturers, One Sabre"
      Original Creator: Jonathan Zittrain Current Version: Samantha Bates
      When the wrongful act must have been committed by one defendant in a group of defendants, but there is no evidence proving that all members of the group acted negligently, should courts refuse to hold the group liable?
      Plaintiff’s eye was injured during a fencing match by a sabre which was defectively manufactured. There was evidence which narrowed the identity of the sabre’s manufacturer to one of the two defendants, but insufficient evidence to link the sabre to a single manufacturer.
  1. 3 Show/Hide More Ravo v. Rogatnick--"The Indivisible Brain Damage"
    Original Creator: Jonathan Zittrain Current Version: Samantha Bates
    If each member of a group of defendants negligently contributes to an indivisible injury, should courts impose liability upon the entire group?
    Plaintiff was severely and permanently retarded due to brain damage suffering at birth. Evidence proved that defendant obstetrician had committed eight separate acts of medical malpractice during the birth, and that the defendant pediatrician had committed three separate acts of medical malpractice after the birth. Expert witnesses maintained that the brain damage could have been caused by either one of the defendants’ negligence, or by the combined negligence of both. However, the experts did not believe that they could accurately tell what “percentage” of the plaintiff’s brain damage was due to obstetrician’s wrongful acts, as opposed to the pediatrician’s.

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July 24, 2017

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Samantha Bates

Research Associate

Harvard Law School, Berkman Center

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