The law of informed consent seeks to actively involve patients in decision making. Most authorities agree that this involvement has not occurred but disagree about why. Some suggest that patients are incapable of understanding medical issues and others that physicians have not explained issues clearly or extensively enough. We observed decision making in several hospital settings and found other significant barriers to patient participation. These barriers include the fact that treatment decisions take place over a long period; there are often many decisions to be made; although patients want information about treatment, they typically believe that decision making is the physician's task; physicians do not understand the rationale for the patient's role in decisions; and the medical decision-making process often involves so many people that the patient does not know who is responsible.