Legal duty to nonpatients: Driving accidents


Question: Driver D strikes a pedestrian after losing control of his vehicle from insulin-induced hypoglycemia. Both Driver D and pedestrian were seriously injured. Driver D was recently diagnosed with diabetes, and his physician had started him on insulin but did not warn of driving risks associated with hypoglycemia. The injured pedestrian is a total stranger to both Driver D and his doctor. Given these facts, which one of the following choices is correct?

A. Driver D can sue his doctor for failure to disclose hypoglycemic risk of insulin therapy under the doctrine of informed consent.

B. The pedestrian can sue Driver D for negligent driving.

C. The pedestrian may succeed in suing Driver D’s doctor for failure to warn of hypoglycemia.

D. The pedestrian’s lawsuit against Driver D’s doctor may fail in a jurisdiction that does not recognize a doctor’s legal duty to an unidentifiable, nonpatient third party.

E. All statements above are correct.

Answer: E. A doctor owes a duty of care only to his/her own patients. This legal duty grows out of the doctor-patient relationship, and is normally owed to the patient and to no one else. However, in limited circumstances, it may be extended to other individuals, so-called third parties, who may be total strangers. Injured nonpatient third parties from driving accidents have successfully sued doctors for failing to warn their patients that their medical conditions and/or medications can adversely affect driving ability.

Dr. S.Y. Tan, emeritus professor of medicine and former adjunct professor of law at the University of Hawaii, Honolulu

Dr. S.Y. Tan

Vizzoni v. Mulford-Dera is a New Jersey malpractice case that is currently before the state’s appellate court. The issue is whether Dr. Lerner, a psychiatrist, can be found negligent for the death of a bicyclist caused by the psychiatrist’s patient, Ms. Mulford-Dera, whose car struck and killed the cyclist. The decedent’s estate alleged that the physician should have warned the patient of the risks of driving while taking psychotropic medications. Dr. Lerner had been treating Ms. Mulford-Dera for psychological conditions, including major depression, panic disorder, and attention deficit disorder. As part of her treatment, Dr. Lerner prescribed several medications, allegedly without disclosing their potential adverse impact on driving. The trial court granted summary judgment and dismissed the case, ruling that the doctor owed no direct or indirect duty to the victim.

The case is currently on appeal. The AMA has filed an amicus brief in support of Dr. Lerner,1 pointing out that third-party claims had previously been rejected in New Jersey, where the injured victim is not readily identifiable. The brief emphasizes the folly of placing the physician or therapist in the untenable position of serving two potentially competing interests when a physician’s priority should be providing care to the patient. It referenced a similar case in Kansas, where a motorist who had fallen asleep at the wheel struck a bicyclist. The motorist was being treated by a neurologist for a sleep disorder.2 The Kansas Supreme Court held that there was no special relationship between the doctor and the cyclist that would impose a duty to warn the motorist about harming a third party.

Other jurisdictions have likewise rejected attempts at “derivative duties” in automobile accident cases. The Connecticut Supreme Court has ruled3 that doctors are immune from third party traffic accident lawsuits, as such litigation would detract from what’s best for the patient (“a physician’s desire to avoid lawsuits may result in far more restrictive advice than necessary for the patient’s well-being”). In that case, the defendant-gastroenterologist, Dr. Troncale, was treating a patient with hepatic encephalopathy and had not warned of the associated risk of driving. And an Illinois court dismissed a third party’s case against a hospital when one of its physicians fell asleep at the wheel after working excessive hours.4

In contrast, other jurisdictions have found a legal duty for physicians toward nonpatient victims. For example, in McKenzie v. Hawaii Permanente Medical Group,5 a car suddenly veered across five lanes of traffic, striking an 11-year-old girl and crushing her against a cement planter. The driver alleged that the prescription medication, Prazosin, caused him to lose control of the car, and that the treating physician was negligent, first in prescribing an inappropriate type and dose of medication, and second in failing to warn of potential side effects that could affect driving ability. The Hawaii Supreme Court emphasized that the risk of tort liability to an individual physician already discourages negligent prescribing; therefore, a physician does not have a duty to third parties where the alleged negligence involves prescribing decisions, i.e., whether to prescribe medication at all, which medication to prescribe, and what dosage to use. On the other hand, physicians have a duty to their patients to warn of potential adverse effects and this responsibility should therefore extend to third parties. Thus, liability would attach to injuries of innocent third parties as a result of failing to warn of a medication’s effects on driving—unless a reasonable person could be expected to be aware of this risk without the warning.

A foreseeable and unreasonable risk of harm is an important but not the only decisive factor in construing the existence of legal duty. Under some circumstances, the term “special relationship” has been employed based on a consideration of existing social values, customs, and policy considerations. In a Massachusetts case,6 a family physician had failed to warn his patient of the risk of diabetes drugs when operating a vehicle. Some 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 invoked the “special relationship” rationale in ruling that the doctor owed a duty to the motorcyclist for public policy reasons.

Dr. Tan is professor 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. For additional information, readers may contact the author at [email protected].


1. Vizzoni v. Mulford-Dera, In the Superior Court of New Jersey Appellate Division, Docket No. A-001255-18T3.

2. Calwell v. Hassan, 925 P.2d 422, 430 (Kan. 1996).

3. Jarmie v. Troncale, 50 A.3d 802 (Conn. 2012).

4. Brewster v. Rush-Presbyterian-St. Luke’s Med. Ctr., 836 N.E.2d 635 (Ill. Ct. App. 2005).

5. McKenzie v. Hawaii Permanente Medical Group, 47 P.3d 1209 (Haw. 2002).

6. Arsenault v. McConarty, 21 Mass. L. Rptr. 500 (2006).


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