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Law enforcement agencies across the United Kingdom successfully lobbied to use a face scanning system acknowledged as biased against women, youths, and members of minority ethnic backgrounds, after complaining that a more accurate version generated fewer potential suspects.

How the System Works

British police use the police national database (PND) to conduct retrospective facial recognition searches. This procedure entails matching a reference photograph of a suspect against a repository of more than 19 million custody photos to find possible hits.

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) found it incorrectly matched Black and Asian people and females at much greater frequency than white men. The Home Office said it “had acted on the findings”.

“It prompts the question of whether this technology only becomes useful if users tolerate discrimination in ethnicity and gender. Convenience is a weak argument for disregarding basic freedoms.”

Known Issue

Internal documents show that this discriminatory flaw has been known about for over twelve months. Furthermore, law enforcement argued to overturn an earlier ruling that was designed to mitigate the problem.

Senior officers were notified of the system's bias in late 2024. The government-ordered NPL review found 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 response, the National Police Chiefs’ Council (NPCC) mandated that the accuracy setting required for potential matches be raised 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 “useful lines of inquiry”. NPCC documents show the higher threshold reduced the number of searches that yielded possible identifications from over half to a just under 15%.

Severe Disparities

Although the authorities refused to say what setting is now in operation, the recent NPL study discovered the system could produce incorrect matches for Black women nearly a hundred times more often than for Caucasian women at specific configurations.

The Home Office stated on these results: “Our evaluation found that in a limited set of circumstances the software is has a greater tendency to wrongly flag some population segments in its match reports.”

Operational Effectiveness vs. Bias

Outlining the impact of the temporary raise to the system's accuracy setting, the police records note: “The change greatly lessens the impact of discrimination across legally safeguarded attributes of ethnicity, generation and sex but had a significant negative impact on police efficiency”. The papers further note that police units complained that “a once effective tactic now delivered results of questionable value”.

Wider Implementation Proposals

Meanwhile, the government has opened a two-and-a-half-month public review on its plans to expand the use of facial recognition technology. The minister for police the relevant minister has described the tool as the “biggest breakthrough since genetic fingerprinting”.

Expert and Oversight Concerns

Abimbola Johnson, head of the advisory panel for the national policing equality strategy, said: “There was very little discussion through 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 undertaken via the race action plan are failing to be integrated into broader operations. Independent assessments have warned that new technologies are being rolled out in a landscape where racial disparities, weak scrutiny and poor data collection continue to exist.

“Any use of this technology must meet strict national standards, be subject to external review, and demonstrate it reduces rather than exacerbates racial disparity.”

Official Statement

A Home Office spokesperson stated: “The Home Office takes the conclusions of the study with utmost gravity and we have already taken action. A updated software has been externally evaluated and procured, which has demonstrated no measurable discrimination. It will be tested in the coming months and will be subject to further assessment.

“The foremost aim is ensuring public safety. This gamechanging technology will assist officers to put criminals and rapists behind bars. There is human involvement in every step of the procedure and no arrest or charge would be taken without trained officers meticulously examining the results.”