10 U.S.C. § 850a — Art. 50a. Defense of lack of mental responsibility

(a) In a court-martial, it is an affirmative defense that, when committing the acts constituting the offense, the accused’s severe mental disease or defect made the accused unable to appreciate the acts’ nature and quality or their wrongfulness. Mental disease or defect is not otherwise a defense. (b) The accused must prove lack of mental responsibility by clear and convincing evidence. (c) When the defense is properly at issue, the military judge must instruct the court members about it and require them to find the accused (1) guilty, (2) not guilty, or (3) not guilty only because of lack of mental responsibility. (d) Subsection (c) does not apply when only a military judge makes up the court-martial. In that situation, when the defense is properly at issue, the military judge must find the accused guilty, not guilty, or not guilty only because of lack of mental responsibility. (e) Despite article 52, the accused must be found not guilty only because of lack of mental responsibility if (1) a majority of the members present when the vote is taken decides the defense was established, or (2) in a judge-only court-martial, the military judge decides it was established.