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Law enforcement agencies across the UK successfully lobbied to deploy a face scanning system known to be biased against women, youths, and members of ethnic minority groups, after complaining that a less biased version generated fewer investigative leads.

How the System Works

UK forces utilize the police national database (PND) to conduct retrospective facial recognition searches. This procedure entails comparing a reference photograph of a person of interest against a repository of over 19 million custody photos to identify potential matches.

Acknowledged Discrimination

The Home Office conceded last week that the technology was flawed. This admission came after a study by the government's National Physical Laboratory determined it incorrectly matched Black and Asian people and females at much greater frequency than white men. The Home Office said it “took steps on the findings”.

“It prompts the issue of whether facial recognition only becomes useful if users tolerate discrimination in race and gender. Operational ease is a weak argument for overriding fundamental rights.”

Known Issue

Official papers reveal that this discriminatory flaw has been known about for over twelve months. Furthermore, police forces argued to overturn an earlier ruling that was designed to address the problem.

Senior officers were informed of the system's bias in late 2024. The Home Office-commissioned laboratory study concluded the system was had a higher probability to produce incorrect matches for images depicting women, individuals of Black ethnicity, and those aged 40 and under.

A Policy U-Turn

In response, the national police leadership body mandated that the accuracy setting required for possible hits be raised to a point where the bias was significantly reduced.

However, this directive was overturned the following month after forces complained that the adjusted system was producing a lower number of “useful lines of inquiry”. NPCC documents indicate the stricter setting reduced the number of queries that yielded potential matches from over half to a mere under 15%.

Profound Inequalities

Although the authorities refused to say what threshold is currently used, the recent NPL study found the system could generate incorrect matches for Black women almost 100 times more frequently than for Caucasian women at certain settings.

The Home Office commented on these results: “Our evaluation identified that in a limited set of circumstances the algorithm is has a greater tendency to wrongly flag some demographic groups in its search results.”

Operational Effectiveness vs. Bias

Outlining the effect of the brief increase to the system's accuracy setting, the NPCC documents state: “This adjustment greatly lessens the effect of discrimination across legally safeguarded attributes of ethnicity, generation and sex but had a substantially detrimental effect on operational effectiveness”. The papers add that forces argued that “a once effective tactic now delivered results of limited benefit”.

Wider Implementation Proposals

Meanwhile, the government has opened a ten-week public review on its proposals to widen the use of biometric scanning systems. Policing minister Sarah Jones has labeled the technology as the “biggest breakthrough since genetic fingerprinting”.

Criticism from Advisors and Monitors

Abimbola Johnson, head of the independent scrutiny and oversight board for the national policing equality strategy, commented: “There was scant consideration through race action plan meetings of the facial recognition rollout despite obvious cross-over with the strategy's goals.

“This disclosure show yet again that the pledges to combat discrimination policing has made via the equality initiative are failing to be integrated into wider practice. Our reports have warned that innovative tools are being rolled out in a landscape where racial disparities, weak scrutiny and poor data collection already persist.

“Any use of this technology must meet rigorous official guidelines, be subject to external review, and prove it reduces rather than exacerbates racial disparity.”

Home Office Response

A government representative stated: “We takes the conclusions of the report seriously and we have already taken action. A updated software has been externally evaluated and acquired, which has no statistically significant bias. It will be tested in the coming months and will be subject to evaluation.

“Our priority is protecting the public. This gamechanging technology will support officers to put criminals and rapists behind bars. There is officer review in every step of the process and no arrest or charge would be pursued without trained officers meticulously examining the results.”