A document expressing a person's wishes about critical care when he or she is unable to decide for him or herself. However, it does not authorize anyone to act on a person's behalf or make decisions the way a power of attorney would.
With an advance directive, individuals have the power to make future decisions about their own critical care without outside influence. A person who wishes or does not wish to be placed upon life support can create an advance directive that will be followed by hospital staff should the person become incapacitated.