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Law enforcement agencies across the United Kingdom effectively campaigned to deploy a facial recognition system known to be discriminatory against women, youths, and members of ethnic minority groups, after complaining that a less biased version generated fewer potential suspects.

How the System Works

British police use the police national database (PND) to conduct retrospective facial recognition searches. This process involves matching a reference photograph of a suspect against a repository of over 19 million mugshots to find potential matches.

Admitted Bias

The Home Office conceded last week that the system was flawed. 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 Caucasian males. The Home Office said it “had acted on the findings”.

“It prompts the issue of whether this technology only becomes effective if users accept discrimination in race and sex. Convenience is a poor argument for overriding fundamental rights.”

Long-Standing Problem

Internal documents reveal that this discriminatory flaw has been known about for more than a year. Furthermore, police forces argued to overturn an earlier ruling that was intended to address the problem.

Senior officers were informed of the system's bias in late 2024. The Home Office-commissioned NPL review found the system was more likely to suggest incorrect matches for images depicting females, individuals of Black ethnicity, and those aged 40 and under.

A Reversed Decision

In reaction, the National Police Chiefs’ Council (NPCC) mandated that the confidence threshold required for potential matches be raised to a point where the bias was significantly reduced.

However, this decision was overturned the next month following complaints from police that the modified technology was producing fewer “investigative leads”. NPCC documents show the higher threshold reduced the number of queries resulting in potential matches from 56% to a just 14%.

Severe Disparities

Although the authorities refused to say what threshold is now in operation, the latest independent review discovered the system could produce false positives for Black women nearly a hundred times more frequently than for white women at specific configurations.

The ministry commented on these findings: “Our evaluation identified that in a limited set of circumstances the algorithm is more likely to wrongly flag some population segments in its search results.”

Balancing Utility and Fairness

Describing the impact of the temporary raise to the system's accuracy setting, the NPCC documents state: “The change greatly lessens the effect of discrimination across legally safeguarded attributes of ethnicity, age and gender but had a significant negative impact on police efficiency”. The documents further note that forces argued that “a previously useful tool now delivered results of limited benefit”.

Broader Rollout Plans

Meanwhile, the government has opened a two-and-a-half-month consultation on its plans to expand the use of facial recognition technology. Policing minister Sarah Jones has described the technology as the “most significant advance since genetic fingerprinting”.

Expert and Oversight Concerns

The chair of a police oversight board, 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 even with obvious cross-over with the strategy's goals.

“These revelations demonstrate yet again that the pledges to combat discrimination the police has made through the race action plan are failing to be integrated into wider practice. Independent assessments have cautioned that innovative tools are being rolled out in a context where racial disparities, inadequate oversight and poor data collection continue to exist.

“All deployment of this technology must meet rigorous official guidelines, be independently scrutinised, and prove it reduces rather than exacerbates racial disparity.”

Home Office Response

A government representative stated: “We takes the findings of the study with utmost gravity and we have already taken action. A updated software has been independently tested and acquired, which has no statistically significant bias. It will be tested in the coming months and will be undergo further assessment.

“Our priority is protecting the public. This gamechanging technology will assist police to apprehend and prosecute offenders. There is human involvement in each stage of the process and no further action would be pursued without specialist personnel carefully reviewing the output.”