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Police forces across the UK successfully lobbied to use a face scanning system known to be discriminatory against women, young people, and individuals from minority ethnic backgrounds, following complaints that a more accurate version produced fewer potential suspects.

The Technology in Practice

British police use the national police database to conduct retrospective facial recognition searches. This process entails matching a “probe image” of a person of interest against a database of over 19 million mugshots to find potential matches.

Admitted Bias

The Home Office conceded last week that the technology was biased. This admission came after a review by the National Physical Laboratory (NPL) determined 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”.

“It prompts the question of whether facial recognition only becomes effective if users tolerate discrimination in race and sex. Convenience is a weak argument for overriding basic freedoms.”

Long-Standing Problem

Official papers reveal that this bias has been recognized for over twelve months. Furthermore, law enforcement argued to overturn an earlier ruling that was intended to mitigate the problem.

Police bosses were informed of the algorithmic discrimination in September 2024. The Home Office-commissioned NPL review found the system was had a higher probability to produce false positives for photos of women, Black people, and those under 40 years old.

A Policy U-Turn

In response, the national police leadership body ordered that the accuracy setting required for potential matches be increased to a level where the disparity was greatly diminished.

However, this directive was reversed the following month after forces complained that the adjusted system was generating a lower number of “useful lines of inquiry”. Internal records indicate the stricter setting reduced the number of searches resulting in potential matches from over half to a just 14%.

Severe Disparities

Although the authorities declined to specify what setting is currently used, the recent NPL study discovered the system could produce false positives for Black women almost 100 times more often than for white women at certain settings.

The Home Office commented on these findings: “Our evaluation identified that in a limited set of circumstances the software is more likely to wrongly flag some demographic groups in its match reports.”

Balancing Utility and Fairness

Describing the effect of the temporary raise to the system's accuracy setting, the police records state: “This adjustment greatly lessens the effect of bias across legally safeguarded attributes of race, generation and gender but had a substantially detrimental effect on operational effectiveness”. The documents further note that forces complained 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 public review on its plans to expand the use of facial recognition technology. Policing minister Sarah Jones has described the technology as the “biggest breakthrough since genetic fingerprinting”.

Criticism from Advisors and Monitors

The chair of a police oversight board, head of the independent scrutiny and oversight board for the police race action plan, commented: “There was scant consideration in 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 anti-racism commitments policing has undertaken via the equality initiative are failing to be integrated into wider practice. Independent assessments have cautioned that new technologies 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 strict national standards, be independently scrutinised, and prove it reduces rather than exacerbates racial disparity.”

Home Office Response

A Home Office spokesperson said: “The Home Office takes the findings of the study with utmost gravity and we have implemented changes. A new algorithm has been externally evaluated and procured, which has no statistically significant bias. It will be trialled in the coming months and will be undergo further assessment.

“The foremost aim is ensuring public safety. This gamechanging technology will assist police to apprehend and prosecute offenders. There is human involvement in every step of the process and no arrest or charge would be pursued without specialist personnel meticulously examining the output.”