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Police forces across the United Kingdom effectively campaigned to use a face scanning system acknowledged as discriminatory against females, young people, and individuals from ethnic minority groups, after complaining that a less biased version produced a reduced number of potential suspects.

How the System Works

UK forces use the national police database to carry out retrospective facial recognition searches. This procedure entails comparing a reference photograph of a person of interest against a repository of over 19 million mugshots to find potential matches.

Acknowledged Discrimination

The Home Office admitted last week that the system was biased. This acknowledgment followed a review by the National Physical Laboratory (NPL) determined it misidentified people of Black and Asian heritage and women at much greater frequency than white men. The Home Office said it “had acted on the findings”.

“This raises the issue of whether facial recognition only becomes effective if users tolerate discrimination in ethnicity and gender. Convenience is a weak argument for disregarding fundamental rights.”

Long-Standing Problem

Official papers show that this bias has been known about for more than a year. Furthermore, police forces lobbied to reverse an earlier ruling that was intended to address the problem.

Senior officers were notified of the system's bias in late 2024. The government-ordered laboratory study concluded the system was more likely to produce false positives for photos of females, Black people, and those aged 40 and under.

A Policy U-Turn

In reaction, the national police leadership body ordered that the accuracy setting required for potential matches be raised to a point where the bias was greatly diminished.

However, this decision was overturned the following month following complaints from police that the adjusted system was generating a lower number of “investigative leads”. NPCC documents show the stricter setting reduced the number of queries that yielded potential matches from over half to a just 14%.

Severe Disparities

Although the Home Office and NPCC declined to specify what threshold is currently used, the latest NPL study found the system could produce incorrect matches for women of Black heritage almost 100 times more frequently than for white women at certain settings.

The Home Office commented on these findings: “Our evaluation identified that in a specific scenarios the algorithm is more likely 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 NPCC documents state: “This adjustment significantly reduces the effect of bias across legally safeguarded attributes of ethnicity, generation and sex but had a substantially detrimental effect on police efficiency”. The documents add that police units argued that “a once effective tactic now delivered outcomes of questionable value”.

Wider Implementation Proposals

Meanwhile, the government has launched a two-and-a-half-month consultation on its plans to widen the use of biometric scanning systems. Policing minister Sarah Jones has labeled the technology as the “most significant advance since DNA matching”.

Criticism from Advisors and Monitors

Abimbola Johnson, chair of the independent scrutiny and oversight board for the police race action plan, said: “We observed very little consideration through race action plan meetings of the facial recognition rollout despite obvious cross-over with the plan’s concerns.

“This disclosure demonstrate yet again that the pledges to combat discrimination policing has undertaken via the race action plan are not being translated into broader operations. Our reports have warned that innovative tools are being rolled out in a context where racial disparities, weak scrutiny and faulty information gathering continue to exist.

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

Official Statement

A government representative stated: “We treat the conclusions of the report seriously and we have implemented changes. A updated software has been independently tested and procured, which has demonstrated no measurable discrimination. It will be tested in the coming months and will be subject to further assessment.

“Our priority is protecting the public. This gamechanging technology will support police to apprehend and prosecute offenders. There is human involvement in each stage of the procedure and no further action would be pursued without specialist personnel meticulously examining the output.”