This paper examines the potential for advance directives to be used by people with mental illness. Also known as a ‘living will’, an advance directive enables a competent person to make decisions about future treatment, anticipating a time when they may become incompetent to make such decisions. In Englishlaw, if “clearly established” and “applicable to the circumstances”, an advance directive assumesthe same statusas contemporaneous decisions made by a competent adult. A psychiatric advance directive, anticipating relapse of a psychosis, develops the concept of the living will. We argue it could reconcile two apparently contradictory themes in the current practice of psychiatry - on the one hand, the call to provide for non-consensual treatment outside hospital, and on the other, the promotion of patient autonomy.