UK Met Police Gangs Violence Matrix
Gangs Violence Matrix (GVM) is a controversial database of thousands of alleged street gang members developed and operated by London's Metropolitan Police Service ('Met Police').
The GVM uses one or more algorithms to rank and categorise people included on the database, based on the risk each 'gang member' poses to others, and the extent to which the police and partner agencies interact with that person.
The GVM (also known as 'Gangs Matrix') has been subject to multiple investigations, research studies, and legal reviews by Amnesty, Liberty, StopWatch, amongst others.
It has also been the subject of a high-profile two-part review (part one, two - pdf) ordered by London mayor Sadiq Khan, and an independent review commissioned by then UK Prime minister David Cameron of England and Wales' criminal justice system by David Lammy MP.
These studies variously conclude that the GVM is inaccurate, discriminates against racial and ethnic minorities, and is, according (pdf) to Amnesty, 'unfit for purpose'.
In 2018, the Met Police's use of Gangs Matrix was served (pdf) with an enforcement notice by the UK privacy commissioner for 'potentially' breaking data protection laws, and for its failure to distinguish victims of crime and offenders. The notice was lifted in 2021.
In October 2022, the Met Police announced it had removed over 1,200 names from the list.
The GVM database has been shrouded in secrecy since it was quietly introduced in 2011.
The Met does not inform people included on the database. Nor is there is any mechanism by which those included can discover what information is help about them, ask for their data to be reviewed or removed, or appeal against their inclusion.
It is unclear whether the GVM is shared with other organisations. Reports indicate it is shared with other UK government departments, including immigration enforcement.
Operator: Metropolitan Police Service (MPS)
Developer: Metropolitan Police Service (MPS)
Sector: Govt - police
Purpose: Predict gang violence risk
Technology: Ranking algorithm
Issue: Bias/discrimination - race, ethnicity, income, geography; Accuracy/reliability; Privacy
Transparency: Governance; Complaints/appeals; Black box
Pyrooz D.C., Decker S., H. (2019). Competing for Control. Gangs and the Social Order of Prisons
Amnesty (2018). Trapped in the Matrix: Secrecy, stigma, and bias in the Met’s Gangs Database (pdf)
Williams P., StopWatch (2018). Being Matrixed: The (Over)Policing of Gang Suspects in London
Scott S., The Monitoring Group (2017). The War on Gangs
Williams P., Clarke B., Centre for Crime and Justice Studies (2016). Dangerous Assocations: Joint enterprise, Gangs and Racism (pdf)
Bridges L. (2015). The Met Gangs Matrix: Institutional Racism in Action
Investigations, assessments, audits
Lammy D. (2018). The Lammy Review
MOPAC (2018). Review of the Metropolitan Police Service Gangs Matrix (pdf)
Met Police (2018 rev 2023). Data Protection Impact Assessment (pdf)
Met Police (2018 rev 2022). Equality Impact Assessment (pdf)
ICO Enforcement Notice (pdf)