--- title: "Giglio v. United States" citation: "Giglio v. United States, 405 U.S. 150 (1972)" authority_id: "AUTH-SCOTUS-GIGLIO-405-US-150" authority_type: "case" jurisdiction: "federal_nationwide" precedential_status: "binding" official_url: "https://www.govinfo.gov/content/pkg/USREPORTS-405/pdf/USREPORTS-405-150.pdf" url: "https://jason93.com/legal/federal-process/authorities/AUTH-SCOTUS-GIGLIO-405-US-150/" legal_review: "2026-08-25" links_checked: "2026-10-15" links_available: 1 links_checked_count: 1 license: "CC BY 4.0" --- # Giglio v. United States ## Holding used An undisclosed nonprosecution promise affecting a key government witness's credibility was attributable to the prosecutor's office and required a new trial under the due-process materiality rule on the case's facts. ## Material limitation The Court did not make every useful impeachment item automatically material or every nondisclosure reversible. Known false testimony and ordinary favorable-evidence suppression must remain analytically distinct. ## Official source and pinpoints 405 U.S. 150, 153–55 (1972): ## Used in - [Arraignment and Pretrial Disclosure](https://jason93.com/legal/federal-process/modules/20-pretrial/arraignment-and-pretrial-disclosure.md)