Sec. 3. (a) A patient is entitled to exercise the patient's constitutional, statutory, and civil rights except for those rights that have been denied or limited by an adjudication or finding of mental incompetency in a guardianship or other civil proceeding.
(b) This section does not validate the otherwise voidable act of an individual who was:
(1) mentally incompetent at the time of the act; and
(2) not judicially declared to be mentally incompetent.