Title 10Armed ForcesRelease 119-73

§949k Defense of lack of mental responsibility

Title 10 › Subtitle Subtitle A— - General Military Law › Part PART II— - PERSONNEL › Chapter CHAPTER 47A— - MILITARY COMMISSIONS › Subchapter SUBCHAPTER IV— - TRIAL PROCEDURE › § 949k

Last updated Apr 6, 2026|Official source

Summary

A person tried by a military commission can claim as a defense that, because of a severe mental disease or defect at the time, they could not understand what they were doing or that it was wrong. Mental illness cannot be used in any other way as a defense. The accused must prove this defense by clear and convincing evidence. If the issue is raised, the judge must tell the panel to return one of three findings: guilty, not guilty, or not guilty by reason of lack of mental responsibility. A “not guilty by reason of lack of mental responsibility” verdict can be returned only if a majority of the members present when the vote is taken agree the defense is proven.

Full Legal Text

Title 10, §949k

Armed Forces — Source: USLM XML via OLRC

(a)It is an affirmative defense in a trial by military commission under this chapter 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 in a military commission under this chapter 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 in a military commission under this chapter, the military judge shall instruct the members as to the defense of lack of mental responsibility under this section and shall charge the members to find the accused—
(1)guilty;
(2)not guilty; or
(3)subject to subsection (d), not guilty by reason of lack of mental responsibility.
(d)The accused shall be found not guilty by reason of lack of mental responsibility under subsection (c)(3) only if a majority of the members present at the time the vote is taken determines that the defense of lack of mental responsibility has been established.

Legislative History

Notes & Related Subsidiaries

Editorial Notes

Prior Provisions

A prior section 949k, added Pub. L. 109–366, § 3(a)(1), Oct. 17, 2006, 120 Stat. 2615, related to the defense of lack of mental responsibility, prior to the general amendment of this chapter by Pub. L. 111–84.

Reference

Citations & Metadata

Citation

10 U.S.C. § 949k

Title 10Armed Forces

Last Updated

Apr 6, 2026

Release point: 119-73