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Police forces across the UK successfully lobbied to use a face scanning system known to be biased against females, youths, and individuals from minority ethnic backgrounds, after complaining that a more accurate version generated a reduced number of investigative leads.

The Technology in Practice

UK forces use the police national database (PND) to conduct retrospective facial recognition searches. This process involves comparing a reference photograph of a suspect against a repository of more than 19 million mugshots to identify possible hits.

Acknowledged Discrimination

The UK interior ministry conceded last week that the system was biased. This admission came after a study by the National Physical Laboratory (NPL) found it misidentified Black and Asian people and women at much greater frequency than Caucasian males. The Home Office said 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 weak argument for overriding fundamental rights.”

Long-Standing Problem

Internal documents show that this bias has been known about for more than a year. Furthermore, law enforcement argued to overturn an earlier ruling that was intended to address the problem.

Police bosses were notified of the system's bias in late 2024. The government-ordered NPL review found the system was more likely to produce incorrect matches for photos of women, Black people, and those under 40 years old.

A Policy U-Turn

In response, the national police leadership body mandated that the confidence threshold required for potential matches be raised to a point where the disparity was significantly reduced.

However, this decision was reversed the following month following complaints from police that the adjusted system was generating a lower number of “investigative leads”. NPCC documents indicate the stricter setting reduced the proportion of searches that yielded potential matches from over half to a just under 15%.

Profound Inequalities

Although the Home Office and NPCC refused to say what threshold is now in operation, the recent NPL study discovered the system could generate incorrect matches for Black women nearly a hundred times more often than for Caucasian women at specific configurations.

The ministry commented on these results: “Our evaluation found 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 temporary raise to the system's accuracy setting, the NPCC documents note: “The change significantly reduces the impact of discrimination across legally safeguarded attributes of ethnicity, generation and gender but had a substantially detrimental effect on police efficiency”. The papers further note that police units complained that “a previously useful tool returned outcomes of limited benefit”.

Wider Implementation Proposals

Meanwhile, the government has opened a two-and-a-half-month public review on its plans to widen the use of facial recognition technology. The minister for police Sarah Jones has labeled 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 national policing equality strategy, said: “There was very little discussion in race action plan meetings of the facial recognition rollout despite obvious cross-over with the strategy's goals.

“These revelations show yet again that the anti-racism commitments the police has made through the equality initiative are failing to be integrated into broader operations. 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 this technology must adhere to strict national standards, be subject to external review, and prove it reduces rather than compounds racial disparity.”

Home Office Response

A government representative said: “We treat the conclusions of the report with utmost gravity and we have already taken action. A new algorithm has been independently tested and acquired, which has no statistically significant bias. It will be trialled in the coming months and will be undergo further assessment.

“The foremost aim is protecting the public. This revolutionary tool will support officers to apprehend and prosecute offenders. There is human involvement in each stage of the procedure and no arrest or charge would be taken without trained officers meticulously examining the results.”