Doull v. Foster

Supreme Judicial Court of Massachusetts · 2021 · Torts

Updated July 23, 2026

TortsNegligenceMedical malpracticeCausationInformed consentJury instructionsbut-for causationfactual cause

Facts

Laura Doull was treated by nurse practitioner Anna Foster at a practice owned by Dr. Richard Miller. Foster prescribed Doull a naturally derived topical progesterone cream in 2008 and did not discuss blood-clot risk because she did not consider it a risk; in spring 2011, Foster also saw Doull three times for shortness of breath and attributed it to asthma and allergies. In May 2011, Doull was hospitalized, diagnosed with a pulmonary embolism and CTEPH, and later died from complications of CTEPH in 2015. At trial, the plaintiffs' expert testified that the cream likely caused blood clots and that earlier diagnosis could have prevented CTEPH, while the defense expert testified there was no evidence the cream increased clotting risk and that Doull's outcome would have been the same even with earlier diagnosis.

Issue

Whether the trial judge erred by instructing the jury on but-for causation rather than a substantial contributing factor standard in a negligence case involving multiple alleged causes and multiple alleged tortfeasors. The court also addressed whether other challenged rulings, including instructions on informed consent, denial of a motion to amend, and restriction on postverdict juror contact, warranted a new trial.

Rule

In the majority of negligence cases, including those involving multiple alleged causes, factual causation is governed by the traditional but-for standard: a defendant's conduct is a factual cause if the harm would not have occurred absent that conduct. Legal causation remains a separate inquiry asking whether the harm was within the scope of the foreseeable risk arising from the negligent conduct. In the rare multiple sufficient cause cases, where two or more competing causes are each independently sufficient and operating at the time of harm, the jury should receive an additional instruction recognizing that each sufficient cause satisfies factual causation without a but-for finding. The substantial contributing factor test should no longer be used in most negligence cases; the court did not disturb its use in toxic tort and asbestos cases because those were not before it.

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One of 10 multiple-choice questions for this case. Pick an answer to see why.

In Portland, Maine, Nora Bennett sued Dr. Elias Rowan for negligently delaying the diagnosis of a heart infection. At trial, Nora also introduced evidence that her preexisting autoimmune disease independently worsened her condition, while the defense presented expert testimony that the heart damage would have occurred when it did even with an earlier diagnosis.

What is the best instruction on factual causation?

Explanation. In most negligence cases, including those involving multiple alleged causes, factual causation is governed by the but-for standard: the defendant's conduct is a factual cause only if the harm would not have occurred absent that negligence. The mere presence of multiple possible causes does not trigger a substantial-factor instruction. (Derived from Doull v. Foster (n.d.).)