A living will is a medical directive written in advance that sets forth an individual's preference for treatment in the event of his or her inability to direct care. Granting power to another person to make medical decisions on your behalf in the event of incapacity is known as a health care proxy. Depending on state law, the documents may be drawn separately, or the living will may be incorporated into the health care proxy. Both directives would come into effect only when you are unable to make health care decisions for yourself. The documents may be drafted to specify when the directives should be initiated (e.g., a life-threatening situation accompanied by unconsciousness).