Massachusetts SJC Restricts Standard of Causation in Cases Involving Multiple Tortfeasors


By: Marc Finkel

In a landmark decision, the Massachusetts Supreme Judicial Court (“SJC”) recently discontinued use of the substantial contributing factor standard of factual causation in matters where multiple sufficient causes of liability may exist amongst multiple defendants. In Doull v. Foster, SJC-12921 (February 26, 2021), the SJC determined that the traditional “but-for” standard of factual causation should be applied under such circumstances. In coming to this conclusion, the SJC adopted the standard proposed in the Restatement (Third) of Torts and effectively eliminated an alternative standard of factual causation previously applied in Massachusetts for over three decades. 

Doull involved claims including, among other things, wrongful death and medical malpractice against a nurse practitioner and a supervising doctor. Following a jury trial, plaintiff appealed a defense verdict in which the primary issue for review was the trial judge’s use of a “but-for” jury instruction for determining the issue of factual causation rather than an instruction based on the substantial contributing factor standard requested by plaintiff. In affirming the trial court’s use of a “but-for” jury instruction as to causation, the SJC found that the substantial contributing factor standard, in general, created too much confusion amongst juries and too often “invite[d] jurors to skip the factual causation inquiry altogether” when assessing liability amongst multiple tortfeasors.   

In its decision, the SJC analyzed prior application in Massachusetts of the substantial contributing factor standard and noted that the application was largely developed in the context of asbestos or other toxic tort claims involving numerous defendants. In these types of claims, although multiple causes of a plaintiff’s injury could arguably be proven, traditional “but-for” causation could not. In Doull, the SJC clarified that in most cases, even where there are multiple defendants, the traditional “but-for” standard is appropriate for determining factual causation because it is the only standard that “ensures that defendants will only be liable for harms that are actually caused by their negligence and not somehow indirectly related to it.” Accordingly, the SJC affirmatively rejected plaintiff’s argument that the substantial contributing factor standard should be used whenever there is evidence of multiple potential causes of a particular harm. 

The SJC noted that its decision in Doull is applicable to most negligence cases. However, specifically, the SJC did not decide whether this decision also applies in toxic tort and asbestos cases, and deferred ruling on that issue. The SJC contemplates in Doull what it may have to do in such cases, including the possibility of keeping a limited exception to the “but-for” standard of factual causation. In the coming years, it is a virtual certainty that the SJC will be tasked with resolving that issue.

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