In clinical negligence, allegations of loss of a chance often arise from an omission to treat or a failure to diagnose, which in turn may deprive the patient of an opportunity of a better outcome. In some U.S. and most Commonwealth jurisdictions, its successful application requires that the underlying condition prior to an individual’s negligence be associated with a better than even chance of cure to begin with.
The controversy arises over what level of risk reduction or lost opportunity is necessary to constitute proximate causation. How large the chance of an adverse outcome and how much of a reduction in that chance are required as a matter of law? Some courts assert that the lost opportunity is relevant only if the plaintiff’s prognosis for survival is better than 50% to begin with, whereas others reject this numerical imperative, especially in cases alleging a delayed diagnosis of cancer.
Proximate cause is the law’s intended mechanism to limit indeterminate liability. Thus, whether a defendant’s negligent conduct constitutes proximate cause is often dispositive in personal injury litigation. However, the term is frequently misunderstood, and has caused much confusion because it has sometimes been used interchangeably with legal cause, or used to include factual cause. And, of course, there can be more than one proximate cause for any given injury.
Reflecting this complexity, the California Supreme Court now disallows confusing jury instructions regarding proximate cause, suggesting instead that the jury be simply directed to determine whether the defendant’s conduct was a contributory factor in the plaintiff’s injury (Mitchell v. Gonzales, 819 P.2d 872 [Cal. 1991]).
Dr. Tan is professor emeritus of medicine and former adjunct professor of law at the University of Hawaii. This article is meant to be educational and does not constitute medical, ethical or legal advice. It is adapted from the author’s book, "Medical Malpractice: Understanding the Law, Managing the Risk" (2006) and his Halsbury treatise, "Medical Negligence and Professional Misconduct" (2012). For additional information, readers may contact the author at siang@hawaii.edu.
