A short overview is given of the current debate on ethics and legal clarification of the range and binding force of so-called living wills demanding interruption of treatment in case of loss of autonomy due to persistent or progressive brain disease. Using the examples of dementia and persistent vegetative states - conditions with growing significance for psychiatrists - the binding force of living wills is examined for cases in which the irreversibility and extent of consciousness loss cannot be predicted with certainty. The range of living wills' authority appears also unclear. Legal proposals for limiting them to disease conditions near death are confronted by other proposals that reject such limitations. Added to this is the medical uncertainty of assessing the criterion nearness to death in irreversible and life-limiting diseases. The patient's right of self-determination, confirmed by high court decisions, to refuse in advance treatments that are life-prolonging but require consent is opposed to the medical obligation to save life and act in the patient's best interest. Moral dilemmas caused by this situation on the part of physicians, carepersons, and relatives or others, particularly authorized persons, should be solved by an exhaustive discussion with all persons who are involved in such decisions, and in a way that comes as near as possible to the patients living will.