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Police forces across the UK effectively campaigned to deploy a facial recognition system known to be biased against women, young people, and members of minority ethnic backgrounds, after complaining that a less biased version generated a reduced number of potential suspects.

How the System Works

British police utilize the police national database (PND) to carry out retrospective facial recognition searches. This procedure involves comparing a “probe image” of a suspect against a repository of over 19 million mugshots to find potential matches.

Admitted Bias

The Home Office admitted last week that the technology was flawed. 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 said it “had acted on the findings”.

“It prompts the issue of whether this technology only becomes effective if users accept discrimination in ethnicity and gender. Operational ease is a weak argument for overriding fundamental rights.”

Long-Standing Problem

Official papers show that this bias has been recognized for more than a year. Furthermore, police forces argued to overturn an initial decision that was intended to mitigate the problem.

Senior officers were informed of the system's bias in late 2024. The government-ordered NPL review found the system was more likely to produce incorrect matches for images depicting women, Black people, and those aged 40 and under.

A Reversed Decision

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

However, this decision was reversed the next month after forces complained that the modified technology was generating fewer “useful lines of inquiry”. Internal records indicate the stricter setting cut the number of searches resulting in possible identifications from over half to a just 14%.

Profound Inequalities

Although the Home Office and NPCC refused to say what threshold is now in operation, the recent NPL study found the system could produce incorrect matches for Black women nearly a hundred times more frequently than for white women at certain settings.

The ministry commented on these findings: “Our evaluation found that in a specific scenarios the algorithm is more likely to wrongly flag some demographic groups in its match reports.”

Operational Effectiveness vs. Bias

Describing the impact of the brief increase to the system's confidence threshold, the NPCC documents state: “The change greatly lessens the impact of bias across protected characteristics of race, generation and sex but had a substantially detrimental effect on police efficiency”. The papers add that police units complained that “a once effective tactic now delivered results of questionable value”.

Wider Implementation Proposals

Meanwhile, the UK administration has launched a ten-week consultation on its proposals to expand the use of facial recognition technology. The minister for police the relevant minister has described the tool as the “most significant advance since DNA matching”.

Expert and Oversight Concerns

The chair of a police oversight board, head of the advisory panel for the police race action plan, said: “There was scant consideration through race action plan meetings of the technology deployment even with clear relevance with the plan’s concerns.

“This disclosure show once again that the anti-racism commitments the police has undertaken through the equality initiative are failing to be integrated into broader operations. Independent assessments have cautioned that new technologies are being implemented in a landscape where ethnic inequalities, weak scrutiny and poor data collection continue to exist.

“All deployment of this technology must meet rigorous official guidelines, be subject to external review, and demonstrate it reduces rather than compounds racial disparity.”

Official Statement

A government representative said: “The Home Office treat the findings of the report seriously and we have implemented changes. A new algorithm has been independently tested and acquired, which has no statistically significant bias. It will be tested in the coming months and will be undergo further assessment.

“Our priority is protecting the public. This revolutionary tool will assist police to put criminals and rapists behind bars. There is human involvement in each stage of the procedure and no arrest or charge would be pursued without trained officers meticulously examining the results.”