Public Law 119-73 (01/23/2026)

10 U.S.C. § 850a

Art. 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 section 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)
section 852 of this title Notwithstanding the provisions of (article 52), 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.

Pub. L. 99–661, div. A, title VIII, § 802(a)(1)100 Stat. 3905Pub. L. 114–328, div. E, title LVII, § 5233130 Stat. 2915(Added , , ; , , .)

Editorial Notes

Amendments

Pub. L. 114–3282016—Subsec. (c). , in introductory provisions, struck out “, or the president of a court-martial without a military judge,” after “the military judge”.

Statutory Notes and Related Subsidiaries

Effective Date of 2016 Amendment

Pub. L. 114–328section 5542 of Pub. L. 114–328section 801 of this titleAmendment by effective on , as designated by the President, with implementing regulations and provisions relating to applicability to various situations, see and Ex. Ord. No. 13825, set out as notes under .

Effective Date

Pub. L. 99–661, div. A, title VIII, § 802(b)100 Stat. 3906

Section 850a of title 10“, United States Code, as added by subsection (a)(1), shall apply only to offenses committed on or after the date of the enactment of this Act [].”
, , , provided that: