One of the most important questions in the ethics of human clinical research asks what obligations investigators owe the people who enroll in their studies. Research differs in many ways from standard care - the added uncertainties, for instance, and the nontherapeutic interventions such as diagnostic tests whose only purpose is to measure the effects of the research intervention. Hence arises the question whether a physician engaged in clinical research has the same obligations toward research subjects that he owes his (...) medical patients, or whether they differ in any fundamental way.Perhaps the most common answer is that the relationship is the same. Investigators, like physicians, are said to be fiduciaries of the volunteers who enroll in research trials. Each owes the best available medical care, which means that a physician can only justify enrolling his patient in research if the study meets the requirements of clinical equipoise, namely, that there is legitimate disagreement within the medical community as to whether the standard treatment or the investigational intervention is superior. (shrink)