In the research ethics literature, there is strong disagreement about the ethical acceptability of placebo-controlled trials, particularly when a tested therapy aims to alleviate a condition for which standard treatment exists. Recently, this disagreement has given rise to debate over the moral appropriateness of the principle of clinical equipoise for medical research. Underlying these debates are two fundamentally different visions of the moral obligations that investigators owe their subjects.Some commentators and ethics documents claim that physicians, whether acting as care givers (...) or researchers, have the same duty of beneficence towards their patients and subjects: namely, that they must provide optimal medical care. In discussing placebo surgery in research on refractory Parkinson's disease, Peter Clark succinctly states this view: “The researcher has an ethical responsibility to act in the best interest of subjects.”. (shrink)