---
kind: "section"
citation: "18 U.S.C. § 17"
title: "18"
title_heading: "Crimes and Criminal Procedure"
number: "17"
heading: "Insanity defense"
release: "119-102"
date: "2026-07-12"
url: "https://uscodex.org/usc/18/17"
units:
  - "Part I — Crimes"
  - "Chapter 1 — General Provisions"
---

# §17. Insanity defense

- (a) **Affirmative Defense.—** It is an affirmative defense to a prosecution under any Federal statute that, at the time of the commission of the acts constituting the offense, the defendant, as a result of a severe mental disease or defect, was unable to appreciate the nature and quality or the wrongfulness of his acts. Mental disease or defect does not otherwise constitute a defense.
- (b) **Burden of Proof.—** The defendant has the burden of proving the defense of insanity by clear and convincing evidence.

## Source credit

(Added Pub. L. 98–473, title II, § 402(a), Oct. 12, 1984, 98 Stat. 2057, § 20; renumbered § 17, Pub. L. 99–646, § 34(a), Nov. 10, 1986, 100 Stat. 3599.)