Loss of Chance Doctrine in Medical Malpractice: Which States Recognize It

By John Mahoney · May 2026 · 13 min read

Consider a patient who arrives in the emergency department with a treatable but aggressive cancer. The defendant physician fails to order the imaging study that would have led to diagnosis. Six months later the cancer is diagnosed elsewhere, but by then it has metastasized and the patient dies. Causation is the case-breaking issue. If the patient's baseline survival chance was, say, 35 percent at the time of the missed diagnosis, can the patient (or the patient's estate) recover for the lost opportunity for cure?

Under traditional but-for causation, the answer is no. The plaintiff cannot prove that, more likely than not, the negligence caused the death, because the patient was more likely than not to have died anyway. The loss-of-chance doctrine emerged precisely to address this scenario, recognizing that the destruction or diminution of a patient's chance for a better outcome is itself a compensable injury distinct from the underlying disease. About half the states have adopted some form of loss-of-chance recovery; the others continue to apply traditional causation rules that bar these claims.

This guide explains the doctrine, traces its development, summarizes the jurisdictions that have adopted and rejected it, and walks through the two main calculation methods. It is intended for plaintiff attorneys evaluating cases where the patient had less than even-odds baseline survival or recovery and conventional causation may be unavailable.

Disclaimer: Loss-of-chance doctrine varies substantially by state and continues to evolve through case law. The summary below is a starting point for research only, not authoritative legal advice. Always consult controlling appellate decisions in the relevant jurisdiction before relying on any specific framework.

The Causation Problem the Doctrine Solves

Traditional tort causation requires the plaintiff to prove that the negligence more probably than not caused the harm. In typical medical malpractice cases, the harm is a deterioration in the patient's condition. The "more probably than not" requirement translates to a probability greater than 50 percent that the negligence caused the harm.

The problem appears in cases where the patient's baseline chance of a good outcome was already less than 50 percent. Many cancers, severe strokes, advanced cardiac disease, and other late-stage conditions have baseline survival or recovery rates below 50 percent. Under strict but-for causation, even egregious negligence in such cases does not satisfy the causation element, because the patient was more likely than not to have suffered the bad outcome regardless.

From a policy standpoint, this result is uncomfortable. It effectively immunizes physicians from liability for negligent treatment of seriously ill patients. The sicker the patient, the less accountability for the provider. The loss-of-chance doctrine is the legal response to that policy concern: it recognizes that the patient's chance of cure or improved outcome has independent value, and that the negligent destruction of that chance is a compensable injury.

The Three Main Approaches to Loss of Chance

Traditional all-or-nothing rule

The traditional rule, still followed in a substantial minority of states, treats loss of chance as no recovery if the baseline probability was below 50 percent and full recovery if it was above 50 percent. Under this rule, the cancer patient with a 35 percent baseline survival chance receives nothing; the cancer patient with a 65 percent baseline survival chance receives full recovery. This rule has been criticized as arbitrary because small changes in baseline probability produce all-or-nothing recovery shifts.

Pure proportional approach

The pure proportional approach, often associated with the Washington Supreme Court's decision in Herskovits v. Group Health Cooperative, treats the lost chance itself as the compensable injury. Damages are calculated as the difference between the patient's baseline chance of a better outcome and the chance after the negligence, multiplied by the value of the better outcome. A patient with a 35 percent baseline chance reduced to 10 percent by the negligence recovers 25 percent of the value of the better outcome.

Relaxed-causation approach (substantial factor)

Some jurisdictions adopt a hybrid: the plaintiff must show that the negligence was a substantial factor in causing the loss, but does not need to satisfy strict but-for causation. Recovery is for the full extent of the patient's actual injury, not a proportional fraction. This approach increases recoveries in loss-of-chance cases but has been criticized as inconsistent with the underlying tort causation framework.

The Falcon v. Memorial Hospital Framework

The Michigan Supreme Court's decision in Falcon v. Memorial Hospital is widely cited for its analytical framework for loss-of-chance cases, even though Michigan has since modified the doctrine by statute. The Falcon framework identified loss of a substantial chance for a better outcome as a distinct compensable interest and proposed a structured proportional analysis.

The framework involves three quantitative steps. First, establish the patient's baseline probability of the better outcome (cure, survival, recovery, function) at the time of the negligence. Second, establish the probability of the better outcome after the negligence reduced or eliminated treatment options. Third, compute the diminution in chance as the difference between the two probabilities. Damages are then proportional to that diminution.

Falcon also addressed the substantial-chance threshold: not every theoretical loss of chance is actionable, only those representing a substantial diminution. Some courts following Falcon impose a percentage threshold (often 20 percent) below which the lost chance is too small to be compensable. Others reject any such threshold and let the jury weigh substantiality.

State-by-State Adoption Summary

The table below summarizes the broad jurisprudential posture of each state on loss of chance as of mid-2026. "Recognized" indicates that the state's highest court has accepted some form of loss-of-chance recovery. "Rejected" indicates that the state's highest court has explicitly refused to adopt the doctrine. "Limited" indicates partial or contingent recognition. "Unsettled" indicates the issue has not been resolved by the state's highest court.

The above is a summary reference compiled from secondary materials and is intended as a starting point. Many jurisdictions have nuanced rules, splits within their case law, or doctrines that overlap with but do not exactly mirror loss of chance (such as the increased-risk-of-harm framework). Always confirm the controlling case law and any statutory modifications in the relevant jurisdiction.

The Calculation Methods in Practice

Proportional damages

In a proportional-damages jurisdiction, the calculation requires four elements: the baseline probability of the better outcome (P_base); the post-negligence probability of the better outcome (P_post); the value of the better outcome (V); and the loss-of-chance damages, equal to (P_base − P_post) × V. The expert testimony required to establish P_base and P_post is the heart of the case.

Consider a patient whose stage I cancer was misdiagnosed and progressed to stage III by the time of correct diagnosis. The expert may testify that the baseline five-year survival rate at stage I was 80 percent, while the post-negligence five-year survival rate at stage III is 30 percent. The loss of chance is 50 percentage points. If the value of the lost five-year survival (loss of life and associated damages) is V, the loss-of-chance damages are 0.5 × V.

Substantial-factor recovery

In a substantial-factor jurisdiction, the plaintiff need not show that the negligence more probably than not caused the harm; the plaintiff must show that the negligence was a substantial factor in producing the harm. If that threshold is met, recovery is for the full extent of the injury, not a proportional fraction.

The substantial-factor approach is more favorable to plaintiffs because it permits full recovery once the threshold is met, but it imposes a less concrete quantitative requirement than the proportional approach. The line between "substantial factor" and "not a substantial factor" is often left to the jury.

Expert Testimony Implications

Loss-of-chance cases require oncology, cardiology, neurology, or other subspecialty experts who can quantify baseline and post-negligence probabilities with reference to peer-reviewed literature. The expert must be able to identify the specific studies, registries, and clinical trials that support the probability estimates.

Sources of probability data

Expert testimony on baseline probabilities typically draws from sources including national cancer registry data, multicenter clinical trial outcomes, peer-reviewed observational studies, and specialty society practice guidelines. The expert should be able to identify the specific data source and explain why it applies to the case's clinical circumstances (patient age, stage, comorbidities).

Cross-examination vulnerabilities

Defense counsel will attack baseline probability estimates on multiple grounds. The data may not be sufficiently recent. The patient may have characteristics that differ from the study population. The clinical scenario may be uncommon and supported only by small case series. The expert must be prepared for each of these lines and ready to defend the probability estimate with specific citations.

Avoiding overstatement

An expert who claims excessive precision (for example, "the baseline survival was 64.7 percent") invites cross-examination on the implied false precision. A more defensible formulation is to present a probability range with explicit assumptions, then explain why the available evidence supports an estimate within that range. This is consistent with how peer-reviewed clinical literature presents probability data.

Strategic Use of the Doctrine

Case selection

Loss-of-chance theory expands the universe of viable plaintiff cases in adopting jurisdictions but requires careful case selection. The strongest loss-of-chance cases involve identifiable failures to diagnose or to treat a condition with established stage-dependent prognosis. Cancer cases (particularly breast, colorectal, lung, and melanoma) are the most common context, followed by cardiovascular events and stroke. The available literature on these conditions provides substantial probability data.

Pleading and proof

In an adopting jurisdiction, the complaint should plead loss of chance as a distinct injury, not merely as an alternative theory of traditional causation. The expert affidavit or certificate should articulate the baseline probability, the post-negligence probability, and the resulting diminution. Failure to plead loss of chance explicitly can result in jury instructions that revert to strict but-for causation.

Damages strategy

In proportional jurisdictions, the damages are mathematically tied to the underlying value of the lost outcome. This requires careful development of the underlying damages (medical expenses, lost earnings, pain and suffering) so that the proportional calculation produces a meaningful recovery. A small percentage of a small underlying value is not a viable case; the underlying damages have to be substantial.

Common Mistakes

• Assuming traditional causation when loss-of-chance recovery is available. The plaintiff may waive a viable theory by pleading only but-for causation.
• Relying on the expert's general impression rather than specific literature. Probability estimates must be tied to peer-reviewed sources.
• Overstating the baseline probability. Defense counsel will pull the same literature and use it to anchor a lower estimate.
• Failing to establish the value of the better outcome. In proportional jurisdictions, the value calculation drives the recovery.
• Confusing loss of chance with increased risk of harm. These are related but distinct doctrines with different elements in some jurisdictions.

Bottom Line

The loss-of-chance doctrine is one of the most consequential tort doctrines in medical malpractice because it determines whether negligent care of seriously ill patients is compensable at all. About half the states have adopted some form of recovery; the others retain traditional causation rules that bar these claims. Plaintiff attorneys evaluating cases involving patients with less than 50 percent baseline outcomes must understand the jurisdictional position, pick the correct theory, and develop the probability evidence through specialty experts and peer-reviewed literature.

For viable cases, the doctrine is a powerful equalizer. For non-viable cases, it cannot rescue a case where the underlying clinical facts do not support a meaningful probability difference. Strong case selection and strong expert development are the differentiators.

Questions? Contact us at [email protected] or (856) 979-6525