A patient who's intoxicated, heavily sedated, or mentally incompetent for any other reason may not be able to give valid consent. If a court has formally declared a patient incompetent, a court- appointed guardian of the person has the power to make medical decisions for him. If an incompetent patient has no legally designated guardian, the doctor must ask the court to appoint one. Some state laws specify who may consent to treatment for an adult who can't do so for himself. Generally, spouses have first priority, followed by adult children and parents.
Most states permit one person to grant the power to make health care decisions to another.
The person with this power can make medical decisions for the patient if the patient becomes unable to do so himself.