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Police forces across the UK successfully lobbied to use a facial recognition system acknowledged as discriminatory against women, young people, and individuals from minority ethnic backgrounds, after complaining that a more accurate version produced fewer potential suspects.

How the System Works

British police utilize the police national database (PND) to conduct searches using historical face recognition. This procedure involves comparing a “probe image” of a suspect against a database of more than 19 million custody photos to find possible hits.

Acknowledged Discrimination

The UK interior ministry admitted last week that the technology was biased. This acknowledgment came after a review by the government's National Physical Laboratory determined it incorrectly matched people of Black and Asian heritage and females at significantly higher rates than white men. The ministry stated it “had acted on the findings”.

“This raises the issue of whether facial recognition only becomes useful if users tolerate discrimination in ethnicity and sex. Convenience is a weak argument for overriding basic freedoms.”

Long-Standing Problem

Internal documents reveal that this bias has been known about for over twelve months. Furthermore, law enforcement argued to overturn an earlier ruling that was designed to address the problem.

Senior officers were notified of the system's bias in September 2024. The Home Office-commissioned laboratory study found the system was more likely to suggest false positives for images depicting women, individuals of Black ethnicity, and those under 40 years old.

A Policy U-Turn

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

However, this decision was reversed the following month after forces complained that the adjusted system was producing fewer “useful lines of inquiry”. Internal records indicate the stricter setting reduced the number of searches that yielded potential matches from over half to a just under 15%.

Severe Disparities

Although the Home Office and NPCC declined to specify what setting is currently used, the latest NPL study discovered the system could produce incorrect matches for women of Black heritage nearly a hundred times more frequently than for white women at specific configurations.

The Home Office commented on these results: “The testing found that in a specific scenarios the algorithm is has a greater tendency to wrongly flag some demographic groups in its search results.”

Operational Effectiveness vs. Bias

Describing the impact of the temporary raise to the system's confidence threshold, the police records state: “This adjustment significantly reduces the impact of discrimination across legally safeguarded attributes of race, age and sex but had a significant negative impact on police efficiency”. The documents add that police units complained that “a previously useful tool returned results of limited benefit”.

Broader Rollout Plans

Meanwhile, the UK administration has launched a two-and-a-half-month public review on its proposals to widen the use of biometric scanning systems. Policing minister Sarah Jones has labeled the tool as the “biggest breakthrough since DNA matching”.

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 scant discussion in race action plan meetings of the facial recognition rollout despite obvious cross-over with the plan’s concerns.

“These revelations demonstrate once again that the anti-racism commitments the police has made through the race action plan are failing to be integrated into broader operations. Our reports have cautioned that new technologies are being rolled out in a context where ethnic inequalities, inadequate oversight and faulty information gathering continue to exist.

“All deployment of facial recognition must meet rigorous official guidelines, be independently scrutinised, and demonstrate it diminishes rather than exacerbates ethnic bias.”

Home Office Response

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

“Our priority is ensuring public safety. This gamechanging technology will support officers to put criminals and rapists behind bars. There is human involvement in every step of the procedure and no further action would be taken without specialist personnel carefully reviewing the results.”