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Law enforcement agencies across the UK effectively campaigned to deploy a facial recognition system known to be discriminatory against women, young people, and individuals from ethnic minority groups, following complaints that a more accurate version generated a reduced number of investigative leads.

How the System Works

UK forces utilize the police national database (PND) to conduct retrospective facial recognition searches. This process entails matching a reference photograph of a person of interest against a database of more than 19 million mugshots to identify possible hits.

Admitted Bias

The UK interior ministry admitted last week that the system was biased. This admission came after a study by the government's National Physical Laboratory determined it incorrectly matched people of Black and Asian heritage and females at much greater frequency than white men. The Home Office stated it “had acted on the findings”.

“It prompts the issue of whether facial recognition only becomes useful if users tolerate biases in ethnicity and gender. Convenience is a weak argument for overriding fundamental rights.”

Known Issue

Internal documents reveal that this discriminatory flaw has been known about for over twelve months. Furthermore, police forces argued to overturn an earlier ruling that was intended to address the problem.

Senior officers were notified of the algorithmic discrimination in September 2024. The government-ordered NPL review concluded the system was had a higher probability to produce incorrect matches for images depicting women, individuals of Black ethnicity, and those under 40 years old.

A Reversed Decision

In response, the National Police Chiefs’ Council (NPCC) mandated that the confidence threshold required for potential matches be increased to a point where the disparity was greatly diminished.

However, this directive was overturned the following month following complaints from police that the modified technology was producing fewer “investigative leads”. Internal records show the stricter setting reduced the proportion of queries that yielded potential matches from 56% to a just 14%.

Profound Inequalities

Although the Home Office and NPCC refused to say what threshold is currently used, the recent independent review found the system could generate incorrect matches for Black women nearly a hundred times more often than for white women at certain settings.

The ministry stated on these results: “Our evaluation found that in a specific scenarios the algorithm is has a greater tendency to incorrectly include some demographic groups in its search results.”

Operational Effectiveness vs. Bias

Describing the effect of the brief increase to the system's accuracy setting, the NPCC documents note: “This adjustment significantly reduces the effect of discrimination across legally safeguarded attributes of race, age and sex but had a significant negative impact on police efficiency”. The documents add that police units complained that “a previously useful tool returned results of limited benefit”.

Wider Implementation Proposals

Meanwhile, the government has opened a two-and-a-half-month consultation on its proposals to expand the use of facial recognition technology. The minister for police the relevant minister has labeled the tool as the “most significant advance since genetic fingerprinting”.

Criticism from Advisors and Monitors

The chair of a police oversight board, chair of the advisory panel for the national policing equality strategy, commented: “We observed very little consideration through race action plan meetings of the technology deployment even with clear relevance with the strategy's goals.

“This disclosure show yet again that the pledges to combat discrimination policing has made through the equality initiative are failing to be integrated into broader operations. Independent assessments have warned that innovative tools are being implemented in a context where racial disparities, inadequate oversight and faulty information gathering already persist.

“All deployment of facial recognition must adhere to strict national standards, be subject to external review, and prove it diminishes rather than exacerbates ethnic bias.”

Home Office Response

A Home Office spokesperson stated: “The Home Office takes the findings of the report with utmost gravity and we have implemented changes. A new algorithm has been externally evaluated and procured, which has no statistically significant bias. It will be trialled in the coming months and will be subject to further assessment.

“The foremost aim is ensuring public safety. This revolutionary tool will assist officers to apprehend and prosecute offenders. There is human involvement in every step of the procedure and no arrest or charge would be pursued without specialist personnel carefully reviewing the results.”