An agent may make a health care decision over the protest of a principal who lacks capacity if:
(1) the directive is irrevocable at times of incapacity;
(2) the directive authorizes the agent to make the health care decision at issue; and
(3) the health care that is to be provided, continued, withheld, or withdrawn is determined and documented by the supervising health care provider to be medically appropriate and is otherwise permitted by law.