Supergrass (informer)

Supergrass is a British slang term for an informant who turns Queen's evidence, often in return for protection and immunity from prosecution. In the British criminal world, police informants have been called "grasses" since the late 1930s, and the "super" prefix was coined by journalists in the early 1970s to describe those who witnessed against fellow criminals in a series of high-profile mass trials at the time.

The first known use of "grass" in that context is Arthur Gardner's crime novel Tinker's Kitchen, published in 1932, in which a "grass" is defined as "an informer". The origin of the term "grass" being used as signifying a traitor, a person who informs on people he or she knows intimately, ostensibly can be traced to the expression "snake in the grass", which has a similar meaning. The phrase derives from the writings of Virgil (in Latin, latet anguis in herba) and has been known in the English language, meaning "traitor", since the late 17th century.

An alternative claim is made for the term originating from rhyming slang, whereby "grasshopper" is defined as "copper", meaning "policeman". The rhyming slang version was supported in 1950 by lexicographer Paul Tempest, who wrote

Grasser. One who gives information. A "squealer" or "squeaker". The origin derives from rhyming slang: grasshopper – copper; a "grass" or "grasser" tells the "copper" or policeman.

In Northern Ireland, the term "supergrass" especially refers to arrested paramilitaries who divulged the identities of their compatriots to the Royal Ulster Constabulary, possibly in exchange for immunity from prosecution. Sir John Hermon did not deny reports that inducements were paid but denied figures as high as £50,000 were involved. The use of the term in Northern Ireland began with the arrest of Christopher Black in 1981. After securing assurances that he would have protection from prosecution, Black gave statements which led to 38 arrests. On 5 August 1983, 22 members of the Provisional IRA were sentenced to a total of more than 4,000 cumulative years in prison, based on Black's testimonies alone (eighteen of these convictions were overturned on appeal on 17 July 1986).

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