The doctrine of informed consent is the center-piece of practical medical ethics, and many of the most pressing controversies in medical ethics pertain to situations where applications of this principle become tricky. For instance, informed consent procedures are disrupted when patients are too sick, too demented, too young, too intoxicated, or otherwise unable to give consent in the normal fashion -- and each of these barriers to informed consent has elicited brisk medical ethics discussions. Behind informed con-sent is the principle of autonomy, namely the belief that patients ought to govern their own medical treatment. This lecture reviews informed con-sent, but then probes further by asking whether or to what extent genuine patient autonomy, and informed consent, are even possible in a medical system where treatment decisions are increasingly shaped by forces outside the patient-physician relationship. lt;brgt;lt;brgt;Griffin Trotter, Ph.D., M.D. is Professor in the Department of Health Care Ethics at Saint Louis University, with a clinical appointment in the Department of Surgery. His recent research focuses on clinical ethics and health policy, especially as they pertain in the medical response to terrorism, and on the relevance of American pragmatism to health care ethics.