A medical centre is an institution established for a specific purpose: to facilitate the health and health-related welfare of the medical centre's patients. Within this institution, there are a variety of professionals who act and interact to serve this purpose. Of particular interest is the interaction between physician and nurse. Generally, the nurse is thought to be under a certain obligation to implement a physician's orders unless there is good reason not to do so. This qualifier places a conflicting obligation (...) upon the nurse not to implement some physician orders. How should a judgement about which orders there is 'good reason' not to implement be made? I propose to approach this question through an analysis of the obligation the nurse has to implement the order of a physician, and the conditions under which the order does not pose such obligations. This analysis will consist of an examination of the obligation in terms of the purposive authority of the physician. For example, in the context of the medical centre, the physician's medical training qualifies her as best able to make determinations of what treatment would promote the patient's health. However, this purpose not only serves as the basis of the physician's authority, but also serves as a limitation upon the physician's authority (for example, an order which would harm the patient would not reflect the purpose for which the physician has been given authority). Thus, a philosophical investigation into the nature of the obligation to implement a physician's orders can help to clarify those occasions when a nurse should not implement an order. (shrink)