Legally, a physician–patient relationship is formed when the physician exercises independent medical judgment on the patient’s behalf. Independent medical judgment is a vague term that is defined by the facts of the given situation. It may involve making a diagnosis, recommending treatment, or implying that no treatment is necessary. As a legal concept, the key is reliance: Did the patient reasonably rely on the physician’s judgment?

A physician may exercise independent medical judgment explicitly or implicitly. A physician who evaluates a patient and establishes a differential diagnosis recognizes that he or she has exercised independent medical judgment. Legal problems usually arise from the implicit exercise of medical judgment. If a physician is not aware of initiating a physician–patient relationship, he or she may injure the patient through inattention. The implicit exercise of medical judgment is best understood through a discussion of common practice situations in which medical judgment is at issue. Since telephone calls pose the most difficult problems in determining whether a physician– patient relationship has been formed, they serve as a useful model to discuss these issues.