Earlier this year, the Massachusetts Supreme Judicial Court ruled that trial courts should use the “but-for” causation standard when evaluating medical negligence cases. This ruling settled prior confusion about the “substantial contributing factor” test that had complicated prior causation analysis. Whether the more streamlined but-for test crosses the New Hampshire border has yet to be seen, but we welcome its arrival should it make the trek.
Case Summary: Doull v. Foster[1]
In 2015, Laura Doull died from complications arising from chronic thromboembolic pulmonary hypertension (CTEPH), a disease associated with blood clot formation in the lungs. Ms. Doull had been a patient of the defendants – a nurse practitioner and supervising physician. The nurse practitioner in 2008 prescribed progesterone cream to assist with Ms. Doull’s premenopausal symptoms, but did not discuss with her the cream’s side effects including blood clots. In the spring of 2011, Ms. Doull experienced shortness of breath which she reported to her supervising physician. She was later diagnosed with CTEPH and underwent emergency surgery to remove lung blockages. She ultimately died from CTEPH-related complications.
Ms. Doull’s family sued her medical providers, asserting the nurse practitioner failed to give proper informed consent about progesterone cream risk; and her physician improperly supervised her treatment and failed to diagnose her pulmonary embolism. At trial, the jury found the two healthcare providers negligent, but concluded their negligence did not cause Ms. Doull’s seizures or subsequent death. The plaintiffs subsequently appealed.
The major issue appellate issue was whether the trial judge properly instructed the jury by using a but-for causation standard:
With regard to this issue of causation, the Defendant in question’s conduct was a cause of the Plaintiff’s harm, that is Laura Doull’s harm, if the harm would not have occurred absent, that is but for the Defendant’s negligence. In other words, if the harm would have happened anyway, that Defendant is not liable.
Plaintiffs argued the trial judge was required to use the substantial factor standard instead of the but-for standard because there were several possible causes of harm and multiple tortfeasors involved in Ms. Doull’s care. The but-for test requires the jury to ask the question: “But for the defendant’s negligence, would the plaintiff’s harm have occurred?” The substantial factor test has the jury determine “whether the defendant’s conduct was a substantial factor in bringing about the plaintiff’s harm.” Defendants supported use of the but-for standard and maintained this approach was in line with Massachusetts law and the Restatement (Third) of Torts.
In February, the Massachusetts Supreme Judicial Court found no error in the trial judge’s instruction and ruled unanimously the but-for test should replace the substantial factor test in most negligence cases, including cases where multiple causes of harm are alleged. Moving away from the “unnecessarily confusing” substantial factor test, the Court stated the but-for causation test provided more clarity to juries in determining factual causation.
History leading up to the Doull Decision
Like New Hampshire, Massachusetts had long required plaintiffs to show a defendant’s actions were the cause-in fact (“factual cause”) and proximate cause of their alleged injury to sustain a negligence claim. The Doull Court described how the but-for and substantial factor causation standards evolved. In its unanimous opinion, the Court noted “the majority of courts around the country and all three Restatements have required but-for causation in most cases” but “there are several situations in which a but-for standard does not work and has been altered to avoid unjust and illogical results.” One situation was where there are multiple sufficient causes:
The classic example involves two separate fires merging and destroying a house . . . If either fire could have independently destroyed the home, then neither fire could be a but-for cause of the harm (because the home would have been destroyed by the other regardless), thereby relieving each of liability under a but-for standard.[2]
Similarly, the Court identified toxic substance exposure and asbestos cases as deserving a more complex causation review. Such scenarios gave way to the departure from but-for causation by providing an alternative causation theory adapted by both the First and Second Restatements of Torts – the substantial factor test. In telling this history, the Court explained the substantial factor test “fixes this problem by relaxing the causal requirement and permitting liability in these circumstances.”
Yet, instead of limiting the substantial factor test to these two scenarios, the Court wrote “the first two Restatements combined the substantial factor terminology and the but-for causation requirement in a confusing manner.” The substantial factor language, consequently, was used generally in negligence cases where “a defendant could not be liable for negligence under the first two Restatements unless the defendant was a ‘substantial factor’ in bringing about the harm.’” In most cases, the Court found “to be a substantial factor, the defendant also had to be a but-for cause of the harm.” While the sole exception to the but-for causation standard was for cases where multiple sufficient causes were alleged, the result was the combination of the but-for and substantial factor standards, which resulted in “blurring the line between factual and legal causation.”
Over the years, the substantial factor test was used in all types of personal injury cases including medical malpractice. Massachusetts defense attorneys urged to the courts to negate the substantial factor test because it broadened the group of liable parties. They were not alone in this fight, as legal scholars wrote the substantial factor test is simply too confusing; a battle which was eventually successful, as the Restatement (Third) of Torts in 2010 abandoned the substantial factor language altogether.[3]
Will New Hampshire move in a similar direction of Massachusetts?
New Hampshire’s 20-year-old civil jury instructions addressing medical negligence causation are analogous to pre-Doull Massachusetts jury instructions:
In order to recover, the plaintiff must prove . . . that the defendant’s acts caused or substantially caused the claimed injuries, which would not have otherwise occurred.[4]
This instruction reflects the first two Restatements, using a combination of but-for and substantial factor language. A challenge to these instructions would be identical to those made by the Doull defendants where multiple causes of harm were alleged. Practically speaking, a successful challenge would limit the pool of defendants in medical malpractice cases to those who were only the but-for cause of the injury. The argument supporting a retreat from the substantial factor test to a but-for test was outlined in the Doull opinion:
There is nothing preventing a jury from assessing the evidence and determining which of the causes alleged by the plaintiff were actually necessary to bring about the harm, and which had nothing to do with the harm.
In light of the Doull decision, the 2010 modifications to the Restatement (Third) of Torts, and the fact that New Hampshire’s civil jury instructions have not been revisited in decades, we believe a Doull-like challenge deserves consideration and is likely to succeed.
[1] 487 Mass. 1 (2021).
[2] The Court is referencing Anderson v. Minneapolis, St. Paul & Sault Ste. Marie Ry. Co., 146 Minn. 430 (1920).
[3] See Restatement (Third) of Torts: Liability for Physical and Emotional Harm, § 26 (2010); see also § 26, cmt. j (arguing against use of the substantial factor test due to the “overuse, abuse, and the confusion generated by it.”).
[4] 1 N.H. Civ. Jury Instructions 13.1 (2020).
