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Law enforcement agencies across the UK effectively campaigned to use a facial recognition system known to be discriminatory against females, youths, and members of minority ethnic backgrounds, following complaints that a less biased version generated fewer potential suspects.

How the System Works

British police use the national police database to carry out searches using historical face recognition. This procedure entails matching a reference photograph of a person of interest against a repository of over 19 million mugshots to identify potential matches.

Admitted Bias

The UK interior ministry conceded last week that the system was flawed. This acknowledgment came after a study by the government's National Physical Laboratory found it incorrectly matched people of Black and Asian heritage and females at much greater frequency than white men. The ministry said it “took steps on the findings”.

“It prompts the question of whether this technology only becomes effective if users tolerate biases in race and gender. Convenience is a poor argument for disregarding basic freedoms.”

Known Issue

Internal documents show that this bias has been known about for more than a year. Furthermore, law enforcement argued to overturn an earlier ruling that was intended to address the problem.

Senior officers were informed of the system's bias in September 2024. The Home Office-commissioned NPL review concluded the system was had a higher probability to produce incorrect matches for images depicting females, Black people, and those under 40 years old.

A Policy U-Turn

In reaction, the national police leadership body ordered that the confidence threshold required for possible hits be raised to a point where the bias was greatly diminished.

However, this directive was reversed the following month after forces complained that the adjusted system was producing fewer “useful lines of inquiry”. NPCC documents show the stricter setting reduced the proportion of searches that yielded possible identifications from 56% to a mere 14%.

Profound Inequalities

Although the authorities refused to say what threshold is now in operation, the latest NPL study discovered the system could generate false positives for Black women almost 100 times more often than for Caucasian women at certain settings.

The Home Office commented on these findings: “The testing found that in a limited set of circumstances the software is has a greater tendency to wrongly flag some population segments in its search results.”

Balancing Utility and Fairness

Outlining the impact of the brief increase to the system's confidence threshold, the police records note: “The change greatly lessens the impact of bias across protected characteristics of ethnicity, age and sex but had a significant negative impact on operational effectiveness”. The documents add that police units complained that “a previously useful tool returned outcomes of limited benefit”.

Wider Implementation Proposals

Meanwhile, the UK administration has launched a ten-week consultation on its proposals to widen the use of facial recognition technology. The minister for police Sarah Jones has labeled the tool as the “biggest breakthrough since DNA matching”.

Expert and Oversight Concerns

Abimbola Johnson, head of the advisory panel for the national policing equality strategy, said: “There was scant consideration in equality strategy sessions of the facial recognition rollout even with obvious cross-over with the strategy's goals.

“This disclosure demonstrate yet again that the anti-racism commitments policing has made via the equality initiative are not being translated into broader operations. Our reports have warned that innovative tools are being rolled out in a landscape where ethnic inequalities, weak scrutiny and poor data collection already persist.

“All deployment of facial recognition must adhere to rigorous official guidelines, be independently scrutinised, and prove it diminishes rather than exacerbates ethnic bias.”

Home Office Response

A Home Office spokesperson said: “We takes the findings of the study seriously and we have already taken action. A new algorithm has been independently tested and procured, which has demonstrated no measurable discrimination. It will be trialled in the coming months and will be subject to further assessment.

“Our priority is ensuring public safety. This revolutionary tool will support 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 specialist personnel carefully reviewing the output.”