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Police forces across the UK effectively campaigned to use a facial recognition system acknowledged as biased against females, young people, and members of ethnic minority groups, after complaining that a less biased version produced fewer investigative leads.

How the System Works

British police use the police national database (PND) to carry out searches using historical face recognition. This process entails comparing a reference photograph of a suspect against a repository of over 19 million custody photos to find potential matches.

Acknowledged Discrimination

The Home Office admitted last week that the system was biased. This acknowledgment followed a review by the government's National Physical Laboratory determined it misidentified people of Black and Asian heritage and females at much greater frequency than white men. The Home Office stated it “took steps on the findings”.

“This raises the issue of whether facial recognition only becomes effective if users accept biases in race and sex. 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 lobbied to reverse an earlier ruling that was designed to mitigate the problem.

Police bosses were notified of the algorithmic discrimination in late 2024. The government-ordered NPL review found the system was had a higher probability to suggest false positives for photos of women, Black people, and those under 40 years old.

A Policy U-Turn

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

However, this directive was reversed the next month following complaints from police that the adjusted system was producing a lower number of “investigative leads”. Internal records indicate the higher threshold reduced the number of queries resulting in possible identifications from over half to a just under 15%.

Severe Disparities

Although the authorities declined to specify what setting is now in operation, the recent NPL study found the system could generate false positives for women of Black heritage almost 100 times more often than for Caucasian women at certain settings.

The ministry stated on these results: “The testing identified that in a specific scenarios the algorithm is more likely to wrongly flag some demographic groups in its match reports.”

Balancing Utility and Fairness

Describing the effect of the brief increase to the system's accuracy setting, the police records note: “This adjustment greatly lessens the impact of bias across legally safeguarded attributes of ethnicity, generation and gender but had a significant negative impact on police efficiency”. The papers further note that forces complained that “a previously useful tool returned outcomes of questionable value”.

Broader Rollout Plans

Meanwhile, the UK administration has launched a two-and-a-half-month public review on its plans to widen the use of biometric scanning systems. Policing minister Sarah Jones has labeled the tool as the “biggest breakthrough since DNA matching”.

Expert and Oversight Concerns

The chair of a police oversight board, chair of the independent scrutiny and oversight board for the police race action plan, said: “We observed scant consideration in race action plan meetings of the facial recognition rollout despite obvious cross-over with the strategy's goals.

“This disclosure show once again that the pledges to combat discrimination the police has made through the race action plan are failing to be integrated into wider practice. Our reports have cautioned that new technologies are being rolled out in a landscape where ethnic inequalities, weak scrutiny and faulty information gathering already persist.

“Any use of facial recognition must meet rigorous official guidelines, be subject to external review, and prove it diminishes rather than exacerbates ethnic bias.”

Home Office Response

A government representative said: “The Home Office treat the conclusions of the study with utmost gravity and we have implemented changes. A updated software has been externally evaluated and procured, which has demonstrated no measurable discrimination. It will be trialled early next year and will be undergo further assessment.

“Our priority is protecting the public. This revolutionary tool will assist police to apprehend and prosecute offenders. There is officer review in each stage of the procedure and no arrest or charge would be pursued without specialist personnel meticulously examining the results.”