Law & Medicine

Law & Medicine: To whom do doctors owe a duty?



Another situation where duty to a third party might arise is the learning of a credible threat of harm directed at a named individual. This is famously known as the Tarasoff doctrine, after a California case in which the court imposed a duty on a college psychologist to directly warn an intended victim of harm by his patient – even though that meant breaching confidentiality of a professional relationship, and the victim was a nonpatient third party (Tarasoff v. Regents of University of California, 551 P.2d 334 [Cal. 1976]).

A doctor may also incur liability for automobile injuries sustained by one other than his or her own patient. In a Hawaii case, a car suddenly veered across five lanes of traffic, striking an 11-year-old bystander. The driver alleged that the prescription medication prazosin caused him to lose control of the car.

In ruling that the health care provider was liable to the injured bystander, the Hawaii Supreme Court held that physicians have a duty to warn their patients of potential adverse medication effects, and this responsibility should extend to third parties (McKenzie v. Hawaii Permanente Medical Group, 47 P.3d 1209 [Haw. 2002]).

A foreseeable and unreasonable risk of harm is an important factor, but not the only decisive factor, in construing the existence of a legal duty. Under some circumstances, the term “special relationship” has been employed based on a consideration of “existing social values, customs, and considerations of policy.”

In a Massachusetts case, a family practitioner had failed to warn his patient of the risk of diabetic drugs when operating a vehicle. Just 45 minutes after the patient’s discharge from the hospital, he developed hypoglycemia, losing consciousness and injuring a motorcyclist who then sued the doctor. The court used the “special relationship” rationale in ruling that the doctor owed a duty to the motorcyclist (Arsenault v. McConarty, 21 Mass. L. Rptr. 500 [2006]).

Dr. Tan is emeritus professor of medicine and former adjunct professor of law at the University of Hawaii, and currently directs the St. Francis International Center for Healthcare Ethics in Honolulu. This article is meant to be educational and does not constitute medical, ethical, or legal advice. Some of the articles in this series are adapted from the author’s 2006 book, “Medical Malpractice: Understanding the Law, Managing the Risk,” and his 2012 Halsbury treatise, “Medical Negligence and Professional Misconduct.” For additional information, readers may contact the author at


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