All procedures using human subjects, from drawing blood to filling out research surveys, require clearance from an institutional review board. The same general philosophy of informed consent guides clinical decisions. Mentally competent adults cannot be forced to accept medical care even under emergency situations. In the case of an unconscious patient in an emergency situation, the law assumes that the person would want to receive treatment. This practice is known as implied consent.
Family members can also provide informed consent on behalf of an impaired patient.
In both the research and clinical setting, the operative principle is that the subject or patient is making an unencumbered free will decision. Many factors can adversely affect the degree of self-determination available to the unfortunate patient in this situation. Some factors are directly related to the patient's medical condition, e.g., clinical and subclinical depression are frequently associated with the development of a terminal illness. Since most patients with a terminal illness are elderly, stressful events like the death of a friend can lead to depression. After treatment for depression, many patients no longer feel suicidal.