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gangs matrix

The gangs matrix*

A handy explainer on the gangs matrix – what it is, how it works, why it is harmful, and what to do if you find yourself on it


In February 2024, the Metropolitan police announced that it had scrapped the gangs matrix, following years of campaigns and legal action from organisations over the disproportionate representation of young Black males on the matrix. The Met will instead use the existing Violence Harm Assessment (VHA) to 'identify and risk assess the most harmful individuals who are involved in violence in London'.

According to the Met:

The VHA is not intended to transfer the personal data of the same individuals who were on the [Gangs Violence Matrix]. Whilst a percentage of individuals who were on the GVM may also feature on the VHA, there will be a significant number who do not meet the VHA scoring criteria. These individuals may feature as part of other processes, however this will be as a result of other information rather than their membership of a gang.

Just like with the Gangs Matrix, a person who is on the VHA will not be informed of this. We therefore still encourage people to check if their name is on the VHA through a Subject Access Request using the guidance below (which remains applicable).

What is the gangs matrix?

The gangs matrix is a police database containing the personal data of persons the Metropolitan police service perceive to be in a gang and likely to commit violence. The Met created the gangs matrix in response to the 2011 riots which started in Tottenham and spread across London and other major cities in England.

At StopWatch, we actively encourage people to check if their name is on the matrix, and support those who wish to get their names and personal details removed from the matrix.

How does the gangs matrix work?

Individuals can be added to the gangs matrix for a variety of reasons, ranging from social media activity, known criminal activity and can be referred by third party institutions such as housing associations, Pupil Referral Units (PRUs) and other children and community services. An individual may not have been involved in any criminal activities to be listed on the gangs matrix. Around a third of individuals on the gangs matrix have never committed a crime.

The gangs matrix uses an algorithm to determine a score which is then colour coded. Each nominal on the database is categorised as either Green, Yellow or Red. The colour is intended to reflect the extent to which that individual poses a risk to others by their level of involvement in a gang. Red denotes those at high risk, Yellow denotes those at a medium risk and Green denotes those who are at a low risk. An individual’s colour score determines the extent to which the police and partner agencies interact with the suspected 'gang member'.

Each London borough creates their own localised matrix and is in charge of adding and removing names. The data is stored and relayed back to a centralised database. The personal data of individuals recorded on the matrix will include some or all the fields of the following information:

  • Full name
  • Nickname
  • Date of birth
  • Home address
  • Ethnicity code
  • Information on whether the individual is a prolific firearms offender or knife carrier
  • Rank and score per matrix criteria
  • Police intelligence information
  • Partner intelligence information

Why is the gangs matrix harmful?

The gangs matrix is the cause of much controversy as it is disproportionately made up of young Black males. In August 2018, StopWatch published a report called Being Matrixed – The (Over)policing of gang suspects in London which highlighted the detrimental impact that being labelled a ‘gang nominal’ had on young people from London.

In addition to StopWatch’s work, Amnesty International have also been campaigning against the use of the gangs matrix. In May 2018, Amnesty published a report called Trapped In The Matrix: Secrecy, stigma, and bias in the Met’s Gangs Database. Amnesty’s report found numerous human rights and data protection issues with the gangs matrix. The composition of the people listed on the database was particularly striking, as:

  • 80% were aged between 16–24 years old
  • 64% were ranked as green or low risk
  • 78% were Black males
  • 75% have been victims of violence
  • 35% have never been convicted of a serious offence
  • 15% were minors

In November 2018, the national regulator for information and data protection law, the Information Commissioner’s Office (ICO) published an enforcement notice. This notice detailed how the gangs matrix breached data protection law on an ongoing basis since its creation in 2011. In particular the Met:

  • Did not process personal data fairly or lawfully. Data was being shared in an unredacted form across a range of public and private bodies. Such sharing was disproportionate and unnecessary to prevent or detect crime
  • Processed personal data excessively in relation to its stated purpose. 64% of individuals were at low/zero risk of gang activity yet were retained on the matrix
  • Processed inaccurate data. Victims of gang related crime were incorrectly presumed to have gang associations themselves. There was no consistency of approach in determining what constituted ‘gang membership’
  • Retained and processed personal data longer than necessary. Even after a person was removed from the matrix, their personal data was retained on an informal list of ‘gang associates’
  • Failed to take appropriate measures to against the unlawful processing or accidental loss of personal data. The data was unencrypted and often transferred in unsecured ways. Information governance was poor. The lack of control over the data in the matrix led to a significant data breach by Newham Council, for which it was fined £145,000 by the ICO

In December 2018, the Mayor of London’s Office for Policing and Crime (MOPAC) published a review of the gangs matrix. Amongst other things, MOPAC’s review remarked that 'the representation of young Black males on the matrix is disproportionate to their likelihood of criminality and victimisation'. The review also found that 38% of people listed on the matrix were assessed as posing no risk of committing violence.

Following public outcry and community pressure as to the unfairness of the matrix, an increasing number of names have been removed from the matrix. Many of the persons removed were Black men below the age of 25.

What happens if I'm on the gangs matrix?

The repercussions of being on the matrix can vary. The ICO’s enforcement notice of November 2018 states that the Met will seek to take enforcement action against identified gang nominals across a range of civil and criminal areas. This means that where prosecution for specific gang-related offences is not possible, 'gang members' are targeted more generally. This can include the disruption of a person’s:

  • Prison license conditions
  • Entitlement to benefits
  • Housing arrangements (including eviction)
  • TV licensing
  • Employment opportunities

The consequences of being on the matrix can also lead to the enforcement of:

  • Increased stop and search
  • Immigration action
  • Parking enforcement / licence conditions
  • School exclusions

How do I know if I'm on the gangs matrix?

To find out if you are on the gangs matrix you can issue a Subject Access Request (SAR) to your local police station. A SAR is an formal request to obtain information on:

  • Whether or not the police is processing your personal data
  • The personal data that the police hold about you and its origin
  • The purpose and legal basis for the processing of your personal data
  • The categories of your personal data being processed
  • The persons (or categories of persons) with whom your personal data has been shared
  • How long your personal data has been stored for, or the criteria used to determine this
  • Your right to request to have your personal data rectified, erased or the processing restricted
  • Your right to complain to the ICO

The police must respond to your SAR within a month.

What do I do if I'm on the gangs matrix?

If you find out that you are on the gangs matrix, you can challenge this by asking the Met to:

  • Erase your personal data from the matrix without undue delay, if (i) processing your personal data will breach the data protection principles; or (ii) the Met has a legal obligation to erase your personal data from the gangs matrix (‘the right to be forgotten’)
  • Correct inaccurate personal data about you, without undue delay (‘right to rectification’)
  • Restrict the processing of your personal data (‘right to restriction’)

Similar to a SAR, the police must respond to your request within a month.

However, the police may refuse these requests if it is necessary and proportionate for them to:

  • Avoid obstructing an official inquiry, investigation or procedure
  • Avoid prejudicing the prevention, detection, investigation or prosecution of criminal offences or the execution of criminal penalties
  • Protect public security
  • Protect national security
  • Protect the rights and freedoms of others

Templates and information on what you will need to take with you can be found below. If you would like some assistance, or have any questions regarding making a Subject Access Request, feel free to contact us:

Please note: this page is not intended to be legal advice and we encourage you to seek professional advice where relevant.