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Police forces across the UK successfully lobbied to use a facial recognition system known to be discriminatory against women, young people, and individuals from ethnic minority groups, after complaining that a less biased version produced fewer investigative leads.

How the System Works

UK forces use the national police database to carry out retrospective facial recognition searches. This procedure entails matching a reference photograph of a suspect against a database of more than 19 million mugshots to identify possible hits.

Admitted Bias

The Home Office admitted last week that the system was biased. This acknowledgment came after a review by the National Physical Laboratory (NPL) found it incorrectly matched people of Black and Asian heritage and women at significantly higher rates than white men. The ministry stated it “took steps on the findings”.

“This raises the issue of whether this technology only becomes useful if users accept discrimination in race and sex. Operational ease is a poor argument for disregarding basic freedoms.”

Known Issue

Official papers reveal that this bias has been known about for more than a year. Furthermore, police forces argued to overturn an initial decision that was designed to mitigate the problem.

Police bosses were notified of the system's bias in late 2024. The Home Office-commissioned laboratory study found the system was more likely to suggest incorrect matches for photos of females, 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 level where the disparity was greatly diminished.

However, this directive was reversed the next month after forces complained that the adjusted system was generating fewer “useful lines of inquiry”. NPCC documents show the higher threshold reduced the proportion of queries resulting in potential matches from over half to a mere 14%.

Profound Inequalities

Although the authorities refused to say what threshold is currently used, the latest independent review found the system could produce incorrect matches for Black women nearly a hundred times more frequently than for Caucasian women at certain settings.

The Home Office commented on these results: “Our evaluation found that in a limited set of circumstances the software is more likely to incorrectly include some population segments in its search results.”

Operational Effectiveness vs. Bias

Describing the impact of the brief increase to the system's accuracy setting, the NPCC documents note: “The change significantly reduces the impact of discrimination across legally safeguarded attributes of ethnicity, generation and sex but had a significant negative impact on police efficiency”. The documents add that forces complained that “a previously useful tool now delivered results of limited benefit”.

Broader Rollout Plans

Meanwhile, the government has launched a ten-week consultation on its proposals to expand the use of biometric scanning systems. Policing minister Sarah Jones has described the technology as the “biggest breakthrough since genetic fingerprinting”.

Expert and Oversight Concerns

Abimbola Johnson, chair of the advisory panel for the national policing equality strategy, said: “There was scant discussion through race action plan meetings of the facial recognition rollout even with clear relevance with the strategy's goals.

“This disclosure show yet again that the anti-racism commitments the police has undertaken via the equality initiative are failing to be integrated into broader operations. Our reports have cautioned that innovative tools are being rolled out in a landscape where ethnic inequalities, inadequate oversight and poor data collection continue to exist.

“Any use of this technology must adhere to rigorous official guidelines, be independently scrutinised, and prove it reduces rather than compounds ethnic bias.”

Official Statement

A government representative said: “The Home Office takes the conclusions of the study with utmost gravity and we have already taken action. A updated software has been independently tested and acquired, which has no statistically significant bias. It will be trialled early next year and will be subject to further assessment.

“The foremost aim is ensuring public safety. This revolutionary tool will assist police to put criminals and rapists behind bars. There is human involvement in every step of the process and no arrest or charge would be pursued without specialist personnel carefully reviewing the output.”