Train tracks interchange leading around a curve as a controlled fire burns on the track during repairs.

COVID-19 and the Problem of Multiple Sufficient Causes

By Nina A. Kohn

Although politicians and pundits warned that businesses would drown in a “tidal wave” of lawsuits seeking to hold them liable for COVID-19 infections, plaintiffs face significant barriers to recovery. Not the least of these is the requirement that a tort plaintiff establish that the defendant was the “actual cause” (or “cause in fact”) of the plaintiff’s injury. This seemingly simple requirement creates a profound barrier to holding even the most negligent, reckless, and bad intentioned actors liable for spreading COVID-19. As others have observed, in a world in which SARS-CoV-2 is increasingly ubiquitous, plaintiffs will often be unable to show that their infections resulted from any particular bad actor’s behavior.

It is in this environment that a seldom used theory of causation — the “multiple sufficient causes” approach — may find new relevance. But it is also in this environment that the American Law Institute (ALI) — an organization comprised of leading lawyers, judges, and academics that publishes influential “Restatements,” or summaries, of common law — is being urged to jettison that theory in the Restatement Third of Torts.

The typical successful tort plaintiff establishes actual causation by showing that, more likely than not, the plaintiff would not have been harmed “but for” the defendant’s actions. The common law of torts, however, has developed alternative ways of establishing “actual causation” when multiple parties contributed to the plaintiff’s harm. For example, the “concert of action” theory allows a plaintiff to hold a defendant liable because the defendant encouraged or induced another to commit a tort, and to do so even if the harm could have occurred without the defendant’s participation.

Similarly, it has long been recognized that where multiple actors simultaneously cause a single harm, each can be held liable, regardless of the fault or lack of fault of the others. The paradigmatic case on the subject, Anderson v. Minneapolis, 146 Minn. 430, 179 N.W. 45 (1920), has been taught to generations of law students. The plaintiff in Anderson sued a railway company whose engine emitted sparks that caused a fire. That fire combined with another of unknown origin, and the resultant combined fire burnt the plaintiff’s property. The railway company was not the “but for” cause of the plaintiff’s damage: the other fire would have been sufficient to cause the full damage. Yet, nevertheless, the railroad company was treated as the actual cause of the harm. For generations, the case has stood for the proposition that a tortfeasor can be held liable for harm where the tortfeasor is only one of multiple sufficient causes of that harm. (The rhetorical device sometimes offered to explain this result is that the tortfeasor was a “substantial factor” in the harm; as Anthony Sebok has documented, this has led it to be confused with situations in which defendants are held liable for toxic torts on the theory that the exposure they occasioned was a “substantial factor” in the plaintiff’s harm.)

The American Law Institute embraced the Anderson approach in Section 27 of the Restatement Third of Torts, which states: “If multiple acts occur, each of which … alone would have been a factual cause of the physical harm at the same time in the absence of other act(s), each act is regarded as a factual cause of the harm.” Despite this, the ALI — as part of its work on another portion of the Restatement — is currently debating whether to bar recovery when the other cause is “non-tortious.” Those arguing in favor of abandoning liability in such situations suggest that it is unfair to hold a defendant liable for harm that would have occurred without tortious behavior.

Whether the ALI jettisons Anderson may not seem like a very big deal. Few modern cases apply Anderson, perhaps because, with modern forensics, it is unusual for two causes to be determined to be truly simultaneous.

And yet, the COVID-19 pandemic presents a situation in which how the law treats “multiple sufficient causes” may be very consequential. Imagine the following hypothetical:

Ellen was very concerned about catching coronavirus because she had asthma. Accordingly, she wore an N95 mask whenever indoors with others and avoided close unmasked contact, even outdoors. However, in January, she made an exception to her protocol by meeting over lunch with two co-workers: A and B. At the time of the lunch, both were COVID-19 positive. At the time, A was unaware of her status and had no reason to think she was COVID-19 positive. However, B knew she was COVID-19 positive. B nevertheless went to the lunch; she thought that Ellen was making a “big fuss” over a “nothing burger” of a virus and should just get it and get over with it. Ellen developed coronavirus and subsequently died of it in March. Ellen’s estate sues B.

Ellen’s estate cannot show that B is the but-for cause of the death: exposure to either co-worker was likely sufficient to cause the harm. Nor can the estate use what is termed “alternative liability theory” — which puts the burden on defendants to prove they are not the cause — because that theory is reserved for situations in which only one of the parties can be the cause. But, under the Anderson line of cases, Ellen’s estate could prevail by showing that B’s behavior was sufficient to cause Ellen’s infection.

The theory is likely to be particularly helpful in situations in which the plaintiff faces simultaneous exposure by a party who lacks capacity for negligence, such as a young child or a person whose cognitive impairment precludes them from understanding the wrongfulness of their behavior. For example, imagine a bed-bound nursing home resident dies after contracting COVID-19. She was simultaneously exposed to the virus by facility staff whom the facility had negligently failed to provide with appropriate personal protective equipment (PPE) and by a fellow resident with a traumatic brain injury. The other resident, unable to appreciate the risk due to her disability, routinely socialized in the now-deceased resident’s room despite the facility making reasonable efforts to segregate COVID-19 positive residents. The other resident’s behavior was not tortious: the exposure was not intentional nor was the behavior unreasonable for an individual with such a disability. If courts refuse to impose liability where one sufficient cause is “innocent,” the facility could avoid liability simply by pointing to the other resident’s behavior.

In short, thanks to the COVID-19 pandemic, what seemed like an antiquated doctrine to be relegated to the age of sparking trains may be steaming back into relevance. The doctrine could enable plaintiffs with COVID-19-related claims to establish causation despite multiple sources of COVID-19 exposure. But if liability is not permitted to attach where one sufficient cause is “innocent” — an approach seriously being considered for the Restatement Third of Torts — we should expect more COVID-19 claims to go off the rails despite clear evidence of wrongdoing.

Nina A. Kohn is a Visiting Professor at Yale Law School and the David M. Levy Professor of Law at Syracuse University.

The Petrie-Flom Center Staff

The Petrie-Flom Center staff often posts updates, announcements, and guests posts on behalf of others.

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