Loss of Chance in Medical Malpractice
Whether a malpractice plaintiff whose preexisting condition already made survival less likely than not can recover when a negligent misdiagnosis or delayed treatment reduced that chance — Herskovits’s pioneering holding that a drop from a 39 percent to a 25 percent chance of survival is enough to take proximate cause to the jury, Massachusetts’s adoption of proportional damages in Matsuyama valuing the lost chance itself rather than the death, Washington’s extension in Mohr to lost chances of a better outcome short of death, Minnesota’s recognition in Dickhoff that a below-even chance of survival has compensable value, Oregon’s treatment in Smith of loss of chance as a standalone injury requiring no relaxed causation — and Kentucky’s refusal in Kemper to abandon the traditional all-or-nothing rule, leaving the doctrine to a sharp state-by-state split.
Recovery for Loss of Chance in Medical Malpractice: The Proportional-Damages Approach and the All-or-Nothing Split
The problem arises because traditional but-for causation demands proof that the malpractice, more probably than not, caused the death — a showing a patient whose underlying disease already gave her less than even odds can never make. The doctrine’s foundational case is Herskovits v. Group Health Cooperative, 664 P.2d 474 (Wash. 1983), where a negligently delayed lung-cancer diagnosis reduced the decedent’s five-year survival odds from 39 percent to 25 percent. "It is undisputed that Herskovits had less than a 50 percent chance of survival at that time," yet the court refused to let that fact end the case: "We hold that medical testimony of a reduction of chance of survival from 39 percent to 25 percent is sufficient evidence to allow the proximate cause issue to go to the jury." The concurrence supplied the analytical move that later courts would formalize — the expert testimony "establishes only that the alleged negligence caused a substantial reduction" in the patient’s long-term chance of survival, so the compensable injury is that reduction itself, not the death.
A quarter century later, Matsuyama v. Birnbaum, 890 N.E.2d 819 (Mass. 2008) gave the doctrine its canonical modern statement in a case of misdiagnosed gastric cancer: "the loss of chance doctrine views a person’s prospects for surviving a serious medical condition as something of value, even if the possibility of recovery was less than even prior to the physician’s tortious conduct. Where a physician’s negligence reduces or eliminates the patient’s prospects for achieving a more favorable medical outcome, the physician has harmed the patient and is liable for damages." On valuation, the court adopted "[t]he most widely adopted of these methods of valuation," the proportional-damages approach, under which loss-of-chance damages are measured as "the percentage probability by which the defendant’s tortious conduct diminished the likelihood of achieving some more favorable outcome." As the court explained, "[t]he formula aims to ensure that a defendant is liable in damages only for the monetary value of the portion of the decedent’s prospects that the defendant’s negligence destroyed."
The adopting jurisdictions have since extended and refined the doctrine. In Mohr v. Grantham, 262 P.3d 490 (Wash. 2011), Washington carried Herskovits beyond death cases: "We hold that Herskovits applies to lost chance claims where the ultimate harm is some serious injury short of death. We also formally adopt the reasoning of the Herskovits plurality," under which "the loss of a chance is the compensable injury" and a plaintiff who lost "a 40 percent chance of survival" recovers "only 40 percent of what would be compensable under the ultimate harm of death or disability (i.e., 40 percent of traditional tort recovery)." Minnesota joined the adopting camp in Dickhoff ex rel. Dickhoff v. Green, 836 N.W.2d 321 (Minn. 2013), reasoning that the doctrine "recognizes that a patient values her chances of recovery or survival and she suffers a real injury when a physician’s negligence reduces that chance, regardless of whether the patient’s chance of survival was above or below 50 percent at the time of the physician’s negligence." The court concluded "that a physician harms a patient by negligently depriving her of a chance of recovery or survival and should be liable for the value of that lost chance," stressing that "we are recognizing that an injury that has always existed is now capable of being proven to a reasonable degree of certainty."
Oregon reached the same destination through injury doctrine rather than causation. In Smith v. Providence Health & Services - Oregon, 393 P.3d 1106 (Or. 2017), a stroke patient alleged that negligent failure to administer timely treatment cost him "a chance for treatment that, 33 percent of the time, provides a stroke victim with a much better medical outcome, with few or no lasting symptoms." The court held that the theory "does not require a relaxation of causation standards. Rather, loss of chance of a better medical outcome is, in itself, a type of harm," and concluded that "we can and should recognize loss of chance as an injury in the context of common-law medical malpractice claims." Kentucky went the other way. In Kemper v. Gordon, 272 S.W.3d 146 (Ky. 2008), the court acknowledged that under "the traditional all or nothing rule, the Gordons would only recover if they could show within a reasonable probability that Dr. Kemper’s failure to diagnose Lori’s stomach cancer caused her death" — and kept that rule, explaining that "there remains great wisdom in ensuring that our laws offer redress for those wronged by medical malpractice based on reasonable probabilities and substantial cause, not on chance or mere possibility." Declaring itself "troubled by the potential financial burden that might be spread upon the shoulders of millions of people if we adopt this new concept of lost or diminished chance of recovery," the court "decline[d] to expand tort liability by judicial legislation in a matter of such far reaching consequence to our citizens."
The doctrinal map is therefore split three ways. A substantial and growing bloc — Washington, Massachusetts, Minnesota, Oregon, and others — treats the lost chance itself as the compensable injury and measures damages proportionally: the plaintiff recovers the value of the ultimate harm discounted by the percentage of chance destroyed, so a drop from 40 percent to 15 percent yields 25 percent of full wrongful-death damages, never a windfall. A second bloc, exemplified by Kentucky and the courts it relied on, adheres to the all-or-nothing rule: a patient whose survival odds were below even at the time of the negligence recovers nothing, however egregious the misdiagnosis, while one who clears 51 percent recovers in full. For practitioners the takeaways are concrete: the viability of a below-even-odds malpractice case is jurisdiction-dispositive and must be checked first; in adopting states the expert work shifts from proving that the negligence probably caused the death to quantifying, to a reasonable degree of medical certainty, the pre- and post-negligence survival percentages that fix the proportional award; and in states following the traditional rule, counsel should frame the proof to reach the more-probable-than-not threshold or expect summary judgment, because the lost chance — however real to the patient — is not an injury the law there recognizes.