18 USC § 17 - Insanity defense

---
identifier: "/us/usc/t18/s17"
source: "usc"
legal_status: "official_legal_evidence"
title: "18 USC § 17 - Insanity defense"
title_number: 18
title_name: "CRIMES AND CRIMINAL PROCEDURE"
section_number: "17"
section_name: "Insanity defense"
chapter_number: 1
chapter_name: "GENERAL PROVISIONS"
part_number: "I"
part_name: "CRIMES"
positive_law: true
currency: "119-84"
last_updated: "2026-04-21"
format_version: "1.1.0"
generator: "[email protected]"
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.)"
---


# § 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.

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**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.)