(20 ILCS 1807/50a)
    Sec. 50a. Article 50a. Defense of lack of mental responsibility.
    (a) It is an affirmative defense in a trial by court-martial that, at the time of the commission of the acts constituting the offense, the accused, as a result of a severe mental disease or defect, was unable to appreciate the nature and quality or the wrongfulness of the acts. Mental disease or defect does not otherwise constitute a defense.
    (b) The accused has the burden of proving the defense of lack of mental responsibility by clear and convincing evidence.
    (c) Whenever lack of mental responsibility of the accused with respect to an offense is properly at issue, the military judge shall instruct the members of the court as to the defense of lack of mental responsibility under this Article and charge them to find the accused:
        (1) guilty;
        (2) not guilty; or
        (3) not guilty only by reason of lack of mental
    
responsibility.
    (d) Subsection (c) does not apply to a court-martial composed of a military judge only. In the case of a court-martial composed of a military judge only, whenever lack of mental responsibility of the accused with respect to an offense is properly at issue, the military judge shall find the accused:
        (1) guilty;
        (2) not guilty; or
        (3) not guilty only by reason of lack of mental
    
responsibility.
    (e) Notwithstanding the provisions of Article 52 of this Code, the accused shall be found not guilty only by reason of lack of mental responsibility if:
        (1) a majority of the members of the court-martial
    
present at the time the vote is taken determines that the defense of lack of mental responsibility has been established; or
        (2) in the case of a court-martial composed of a
    
military judge only, the military judge determines that the defense of lack of mental responsibility has been established.
(Source: P.A. 99-796, eff. 1-1-17.)