Law & Medicine

Legal duty to nonpatients: Communicable diseases


Question: Dr. X incorrectly informs his patient Y that he is HIV negative, when in fact he had tested positive. As a result, treatment was delayed for a year. In the meantime, Y infects his sexual partner Z, who is not Dr. X’s patient, and whom the doctor has never met. In a negligence lawsuit by Z against Dr. X, which of the following is best?

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

Dr. S.Y. Tan

A. Legal duty is used as a filter to control the tide of litigation and to prevent “liability in an indeterminate amount for an indeterminate time to an indeterminate class.”

B. Duty of care arises from the doctor-patient relationship and is usually owed to the patient and no one else.

C. Even if Dr. X were negligent, Z must first establish that the doctor owes her a duty of due care.

D. As a nonpatient “third party,” Z has the burden of convincing the court that she was a known, foreseeable victim of a serious condition and was in a special relationship.

E. All correct.

Answer: E. The law requires that a professional acts reasonably with the knowledge, skill, and judgment ordinarily possessed by fellow members in good standing. For the medical profession, this duty of due care springs from the doctor-patient relationship, and is generally owed to the patient and to no one else. Allowing individuals outside the relationship, i.e., nonpatient third parties, a cause of action against the provider will unwisely expand the sphere of medical liability. Besides, an expansive view of legal duty may lead the provider to breach confidentiality or invite intrusive and/or irrelevant inquiries into a patient’s personal matters. Ascertaining whether a defendant owes a duty to a claimant is the first inquiry in the tort of negligence. To say there is no duty owed is to deny liability altogether, however obvious the breach or horrendous the foreseeable injuries. Thus, duty is used as a filter mechanism to reduce frivolous suits or otherwise control the tide of litigation, to prevent “liability in an indeterminate amount for an indeterminate time to an indeterminate class” as famously articulated in the 1928 Plasgraf case.1

Still, a health care provider can sometimes be found liable to one other than his or her immediate patient, notwithstanding the absence of a provider-patient relationship with that person. One such class of claims deals with communicable diseases. In Bradshaw v. Daniel,2 the Supreme Court of Tennessee held that a physician has a duty to inform a patient’s immediate family of the risk of an infectious disease such as Rocky Mountain spotted fever, although the condition itself is not contagious without a vector. In Shepard v. Redford Community Hospital,3 a lower court found no physician-patient relationship between the doctor and the patient’s son who died after contracting meningitis from his mother, who had the disease first, but was not warned of the risk of spreading it to family members. The appellate court reversed, finding liability and holding that the physician-mother relationship resulted in a special situation for imposing a duty of care for her son.

A nonpatient can sue providers who have failed to advise their patients of the sexual transmissibility of conditions such as AIDS or hepatitis B. In DiMarco v. Lynch Homes-Chester County Inc.,4 the Supreme Court of Pennsylvania found liability where the physician’s failure to advise his patient to abstain from sexual activity for an appropriate period of time led to the sexual partner acquiring hepatitis B. The Court used a “foreseeable orbit of risk of harm” argument, stating: “If a third person is in that class of persons whose health is likely to be threatened by the patient … [she] has a cause of action … because the physician should recognize that the services rendered to the patient are necessary for the protection of the third person.” And in Reisner v. Regents of the University of California,5 a 12-year-old girl became infected with HIV after receiving tainted blood, but the defendant did not disclose the information in a timely manner. She died of AIDS at age seventeen, but not before infecting her sexual partner, who was the plaintiff in the case. The court held that a physician fulfills his duty only after he warns the patient of the risk to others, and that the lack of knowledge of the third party’s identity was immaterial.

Liability may be more likely in jurisdictions that impose a statutory duty on physicians to inform, counsel, or warn their patients or inform health authorities of conditions such as AIDS. California allows the attending physician to disclose to “a person reasonably believed to be the spouse … a sexual partner or a person with whom the patient has shared the use of hypodermic needles, or to the local health officer.”6 Although this statutory disclosure is permissive rather than mandatory, it may prove persuasive in any court’s deliberation over the “no-duty” defense argument.

A recent case7 presents an interesting fact-situation on the duty issue. Dr. CC incorrectly told his patient that he tested negative for a sexually transmissible disease (herpes), when in fact he had tested positive. His girlfriend, who was not Dr. CC’s patient, became infected and filed suit. The trial court dismissed, ruling that the doctor owed no duty to the girlfriend, because she was not his patient and therefore she had no “legally cognizable claim.” Connecticut’s highest court has recently heard oral arguments on appeal, and its decision is pending.

The AMA has filed an amicus brief in support of Dr. CC.8 It argues that Connecticut’s precedent mitigates against expansion of a provider’s duty to nonpatients and raises public policy concerns such as impact on malpractice insurance rates, patient care, and the ethics of patient confidentiality. The brief concluded that it was “… nearly impossible to articulate a bright-line rule of foreseeability … when, like here, the class of persons potentially exposed to injury from such care is so broad and cannot be readily identifiable at the time care is rendered.”


1. Palsgraf v. Long Island Railroad Co., 248 N.Y. 339, 162 N.E. 99 (1928).

2. Bradshaw v. Daniel, 854 S.W.2d 865 (Tenn. 1993).

3. Shepard v. Redford Community Hospital, 390 N.W.2d 239 (Mich. App. 1986).

4. DiMarco v. Lynch Homes-Chester County Inc., 583 A 2d 422 (Penn. 1990).

5. Reisner v. Regents of the University of California, 37 Cal Rptr 2d 518 (Cal App 2 Dist., 1995).

6. California Health & Safety Code §121015 (a).

7. Doe v. Cochran, 62 Conn L Rptr 33, 2016 (S.C. #19879).

8. What duties do physicians owe to non-patients? AMA News. 2018 Jul 13.

Dr. Tan is Emeritus 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

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