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Police forces across the United Kingdom effectively campaigned to use a facial recognition system acknowledged as discriminatory against females, youths, and members of minority ethnic backgrounds, following complaints that a more accurate version produced fewer potential suspects.

How the System Works

British police use the police national database (PND) to carry out retrospective facial recognition searches. This process involves comparing a “probe image” of a person of interest against a database of more than 19 million mugshots to find possible hits.

Admitted Bias

The Home Office conceded last week that the technology was biased. This admission followed a study by the government's National Physical Laboratory found it misidentified people of Black and Asian heritage and females at much greater frequency than Caucasian males. The Home Office stated it “took steps on the findings”.

“This raises the issue of whether facial recognition only becomes useful if users accept biases in race and gender. Operational ease is a poor argument for overriding fundamental rights.”

Long-Standing Problem

Official papers show that this bias has been recognized for over twelve months. Furthermore, law enforcement argued to overturn an earlier ruling that was designed to address the problem.

Police bosses were informed of the system's bias in late 2024. The Home Office-commissioned laboratory study found the system was more likely to produce incorrect matches for images depicting females, Black people, and those under 40 years old.

A Reversed Decision

In response, the National Police Chiefs’ Council (NPCC) mandated that the accuracy setting required for possible hits be increased to a level where the disparity was greatly diminished.

However, this decision was overturned the next month after forces complained that the adjusted system was generating a lower number of “useful lines of inquiry”. Internal records indicate the higher threshold cut the number of searches that yielded potential matches from over half to a mere under 15%.

Severe Disparities

Although the Home Office and NPCC refused to say what threshold is currently used, the latest NPL study found the system could generate false positives for Black women almost 100 times more often than for white women at specific configurations.

The ministry commented on these findings: “The testing identified that in a specific scenarios the software is more likely to incorrectly include some demographic groups in its match reports.”

Balancing Utility and Fairness

Outlining the impact of the brief increase to the system's confidence threshold, the NPCC documents note: “This adjustment greatly lessens the effect of discrimination across legally safeguarded attributes of race, age and sex but had a significant negative impact on police efficiency”. The documents add that forces complained that “a previously useful tool now delivered results of limited benefit”.

Wider Implementation Proposals

Meanwhile, the UK administration has launched a two-and-a-half-month consultation on its proposals to widen the use of biometric scanning systems. Policing minister the relevant minister has described the tool as the “biggest breakthrough since genetic fingerprinting”.

Criticism from Advisors and Monitors

The chair of a police oversight board, chair of the independent scrutiny and oversight board for the police race action plan, commented: “There was very little consideration in race action plan meetings of the technology deployment despite clear relevance with the plan’s concerns.

“These revelations show yet again that the anti-racism commitments policing has made via the race action plan are not being translated into wider practice. Independent assessments have warned that innovative tools are being rolled out in a landscape where racial disparities, weak scrutiny and faulty information gathering already persist.

“All deployment of this technology must adhere to rigorous official guidelines, be independently scrutinised, and prove it reduces rather than exacerbates ethnic bias.”

Official Statement

A government representative said: “We treat the conclusions of the report seriously and we have implemented changes. A new algorithm has been independently tested and acquired, which has no statistically significant bias. It will be trialled early next year and will be undergo evaluation.

“Our priority is ensuring public safety. This gamechanging technology will assist officers to apprehend and prosecute offenders. There is officer review in each stage of the procedure and no arrest or charge would be taken without specialist personnel carefully reviewing the output.”