(1) AFFIRMATIVE DEFENSE.—All persons are presumed to be sane. It is an affirmative defense to a criminal prosecution that, at the time of the commission of the acts constituting the offense, the defendant was insane. Insanity is established when:
(a) The defendant had a mental infirmity, disease, or defect; and
(b) Because of this condition, the defendant:
1. Did not know what he or she was doing or its consequences; or
2. Although the defendant knew what he or she was doing and its consequences, the defendant did not know that what he or she was doing was wrong.
Mental infirmity, disease, or defect does not constitute a defense of insanity except as provided in this subsection.
(2) BURDEN OF PROOF.—The defendant has the burden of proving the defense of insanity by clear and convincing evidence.