[Self determination of patients in social psychiatric practice. A medical ethics model and its practical application].

To protect patients' autonomy, valid informed consent must be given prior to medical treatment. This includes disclosure of information, understanding, ability to decide freely, and competence/capacity of the patient. However, a psychiatric disorder may disturb the ability to make a choice of their own. These patients have lost their competence to give valid informed consent. In everyday practice of social psychiatry, it is of particular interest to have objective and valid criteria to identify the incompetent patient. These problems are discussed in a case report, and four criteria (understanding, reasoning, decision making and appreciation of the disorder) are presented to diagnose the patients' competence.