Turn state's evidence
legal term for one who testifies as a witness for the state
A criminal turns state's evidence by admitting guilt and testifying as a witness for the state against their associate(s) or accomplice(s), often in exchange for leniency in sentencing or immunity from prosecution. The testimony of a witness who testifies against co-conspirator(s) may be important evidence.
According to a 2008 United Nations Office on Drugs and Crime document, persons who turn state's evidence "are known by a variety of names, including cooperating witnesses, crown witnesses, snitches, witness collaborators, justice collaborators, state witnesses, 'supergrasses', macarons and pentiti (Italian for 'those who have repented')."
United Kingdom
In the United Kingdom and the Commonwealth realms, the term is to turn Queen's or King's evidence, depending on the sex of the reigning monarch. The term "turning approver" or "turn king's approver" was also historically used, especially in Ireland; an approver "not only admitted his own guilt to a crime but also incriminated his accomplices both past and present" in exchange for avoiding a death sentence (and obtaining a lesser penalty, such as life imprisonment or abjuration of the realm) or improving prison conditions. It has its origins in the 16th century, and allowed a person to become a crown witness and avoid pleading guilty. Even at this early stage, the courts saw crown witness testimony as less reliable than other evidence, because it was encouraged in return for better treatment before the law. In 1751, regulations were introduced, stipulating that crown witness testimony should be corroborated with independent, third-party evidence.
Crown witnesses known as supergrasses were used during the Northern Ireland conflict. In the 1980s, about 30 members of paramilitary groups (both loyalist and republican) gave the authorities evidence against their former comrades in exchange for a more lenient sentence (or immunity from prosecution), as well as a new identity to protect them from retribution. Supergrass testimony was used, for example, in trials against IRA members.
“Turn state's evidence” enters the record as legal term for one who testifies as a witness for the state. Crown Archives preserves that source wording while asking what Turn, state's and evidence can confirm, complicate or overturn.
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The citation trail is more important than the brevity of the summary: it shows where individual claims can be examined in context. The source revision retrieved here is dated Nov 11, 2025. The linked authority identifier is Q1640069. The Library of Congress control number is sh89001263. 1 of 1 selected statements include explicit references; 0 carry qualifiers and 0 use preferred rank. The first chronological checks are 2008 and 1751.
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