This article provides a historical, ethical, and conceptual review of medical futility disputes in the intensive care unit (ICU). Particular emphasis is placed on the role that physician power plays in these disputes. Specifically, the article analyzes the circumstances and arguments proposed to justify when physicians may stop life-sustaining treatment without the consent of either the patient or surrogate. The article begins by reviewing the history of the medical futility movement and the causes of medical futility disputes. Second, the major positions and policy statements addressing how such disputes should be resolved are summarized. Third, the article turns from an objective, descriptive approach to a more normative approach by highlighting the value-laden nature of most “futility” judgments regarding potentially inappropriate treatment. Finally, an outline of how clinicians should respond to requests for ICU interventions that they deem medically or ethically inappropriate is provided.