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Massachusetts Adoption of the “But-For” Factual Causation Standard in Multiple Defendant Tort Actions and Its Impact on Toxic Tort Litigation

On February 26, 2021, the Massachusetts Supreme Judicial Court (SJC) clarified the standard to be used for factual causation in multiple defendant tort actions. The SJC’s opinion in Doull v. Foster, 487 Mass. 1 (2021), changed the standard for factual causation from the confusing “substantial contributing factor” test to the more straightforward “but for” causation standard.

The SJC differentiated cases with multiple sufficient causes, such as asbestos and other toxic tort matters, due to the difficulty in establishing “which particular exposures were necessary to bring about the harm.” [Doull at p. 14]. The Court did, however, leave open the possibility that it may also replace the “substantial factor” test in those cases as well.  This potential for a new causation standard has created tremendous uncertainty as to which standard will be used for toxic tort cases in Massachusetts going forward.

Causation Standards in Massachusetts:

In Massachusetts, the two causation tests in tort cases are: the substantial factor test and the but-for causation test. The substantial factor test concludes that a defendant is liable if the defendant’s actions were a “substantial contributing cause” of the injury; importantly, there can be multiple substantial contributing causes. O’Connor v. Raymark Industries, Inc., 401 Mass 585 (1988). This test has been traditionally applied in two situations: (1) cases involving multiple sufficient causes of a harm; or (2) cases involving toxic tort/asbestos cases. [Doull at p. 7]. The but-for test concludes that a defendant is the factual cause of a harm if that harm would not have occurred “but-for” the defendant’s negligence. [Doull at p. 7]. The but-for standard has a clear focus on the principle that a defendant cannot be held liable unless the defendant’s conduct is casually related to plaintiff’s injuries. [Doull at p. 5, citing Glidden v. Maglio, 430 Mass. 694 (2000)].

One of the reasons why the substantial factor test is problematic and causes for confusion is because juries may focus more on the “substantial” portion of the negligence instruction, rather than the actual causal link between a defendant’s action and plaintiff’s injury. [Doull at p. 15]. A defendant’s actions may be substantial, yet not the cause of plaintiff’s harm. The SJC in Doull held that the but-for test was much clearer and more straightforward in its application, even in situations involving multiple potential causes of harm.

The Doull Decision:

In the Doull case, Laura Doull was treated with hormone-replacement drugs to treat perimenopause-related symptoms. She ultimately developed pulmonary issues and in 2015 died at the age of 43 from a rare condition known as chronic thromboembolic pulmonary hypertension, which resulted from a blood clot in her lungs. Prior to her death, Doull and her family members filed suit against two of her providers, alleging negligence, as well as other claims, with respect to her care.

During trial, the judge instructed the jury using the but-for causation test to evaluate the defendants’ negligence. The jury found for the defendants and the plaintiff appealed arguing the substantial factor test should have been the causation standard instruction to the jury. On appeal, the SJC found no error in the court’s instruction and further ruled that due to its confusing and unclear nature, the substantial factor test is to be discontinued in nearly all tort cases, including those with multiple sufficient causes of harm, bur specifically excluded toxic tort cases, such as asbestos cases.

Impact of the Doull Decision in Multiple Defendant Negligence Actions:

The Doull decision clarifies the instruction to be given to the jury in cases where there are multiple defendants, or multiple claims arising out of a tort.  In the past, plaintiffs would often argue that the “substantial factor” test should be used, while defendants argued a “but for” standard.  The trial judge would then make a decision.  The Doull decision now provides clarification and certainty as to the correct instruction to be given.  No longer will juries have to figure out what a “substantial factor” means, but rather will simply use the straightforward but-for test.

Impact of the Doull Decision in Toxic Tort Cases:

In Doull, the Court did not have an opportunity to analyze the causation standard in connection with toxic tort cases, such as asbestos cases, to determine if the but-for standard should be applied to those cases as well. While the Court clarified the appropriate standard for causation to be applied in most negligence cases, it was reluctant to do so in the context of toxic tort cases. As the Court noted in a footnote, the issue of causation in toxic tort asbestos cases is not before it in Doull, therefore, “we do not disturb our decision in O’Connor or the use of the substantial contributing factor instruction in those cases.” [Doull at p. 29]

As a result, the Doull case explicitly left the door open as to whether there will be a shift in toxic tort cases from the substantial factor test to the but-for standard. As the Court points out, toxic tort litigation matters present unique features including “factual and scientific limitations” that complicate establishing causation. The Court noted, that “in an appropriate case, however, we may consider whether to replace the substantial contributing factor test in these cases as well. There appears

to be a variety of approaches taken in these cases, and a decision on whether to replace the substantial contributing factor test would benefit from full briefing and argument.” Id.  By the language, the SJC certainly signaled that it is open to replacing the substantial factor as the causation test for toxic tort cases, whether that be with the but for causation or whether it may find some middle ground between but-for and substantial cause.

About The Author

Siobhan M. Surette

Siobhan Surette is a member of the firm’s litigation group, her practice includes defending both individuals and businesses in a wide… Read More

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