Supergrass informant term origins and its role in Northern Ireland

The term “supergrass” first appeared in British journalism in the early 1970s to label informants who turned King’s evidence in exchange for immunity, building on the slang “grass” that had been used for informers since the late 1930s [1]. Its etymology links back to Arthur Gardner’s 1932 novel Tinker's Kitchen, where “grass” meant an informer, and possibly to the older phrase “snake in the grass” that denoted a traitor [1]. An alternative origin points to rhyming slang—“grasshopper” for “copper” (policeman)—a theory supported by lexicographer Paul Tempest in 1950 [1].

In Northern Ireland, “supergrass” became synonymous with arrested paramilitaries who testified against comrades, often for promised protection from prosecution. The first high‑profile case began with Christopher Black’s arrest in 1981; after securing assurances of safety, Black’s statements led to 38 arrests and, on 5 August 1983, 22 Provisional IRA members received sentences totalling more than 4,000 years [1]. By the end of 1982, another 25 “supergrasses” had surfaced, contributing to the detention of over 600 individuals from groups such as the IRA, INLA and UVF. Notable testimonies included those of Joseph Bennett (UVF, April 1983), Kevin McGrady (July 1983, described by Lord Chief Justice Robert Lowry as “bizarre, incredible and contradictory”) [1], and Harry Kirkpatrick (INLA, December 1985).

However, many convictions based on supergrass evidence were later overturned. Eighteen of the 22 IRA convictions from Black’s testimony were reversed on appeal in July 1986, and the UVF and INLA cases faced similar reversals in December 1984 and December 1986 respectively [1]. The high rate of overturned judgments led to the discontinuation of the supergrass system in 1985, though it was revived in 2011 for the murder trial of UDA member Tommy English [1]. The Police Service of Northern Ireland now prefers the term “assisting offender” to avoid the stigma attached to “grass” or “supergrass” [1].

The legacy of the supergrass approach is mixed. On one hand, it enabled authorities to secure large numbers of arrests and temporarily cripple paramilitary networks; on the other, the reliance on incentivized testimony raised questions about reliability, as reflected in the numerous overturned convictions. The practice’s revival in 2011 suggests that law‑enforcement still sees value in insider testimony, yet the historical record warns of the legal and ethical pitfalls that accompany such deals. Whether future supergrass prosecutions will withstand appellate scrutiny remains an open question for the justice system in Northern Ireland.