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Police forces across the United Kingdom successfully lobbied to use a face scanning system acknowledged as biased against females, young people, and members of ethnic minority groups, after complaining that a less biased version generated fewer potential suspects.

The Technology in Practice

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

Admitted Bias

The Home Office conceded last week that the technology was flawed. This admission came after a review by the government's National Physical Laboratory found 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 this technology only becomes effective if users accept biases in ethnicity and gender. Convenience is a weak argument for overriding basic freedoms.”

Long-Standing Problem

Official papers show that this bias has been known about for more than a year. Furthermore, law enforcement argued to overturn an earlier ruling that was designed to mitigate the problem.

Police bosses 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 women, Black people, and those under 40 years old.

A Reversed Decision

In reaction, the National Police Chiefs’ Council (NPCC) mandated that the accuracy setting required for potential matches be raised to a point where the bias was greatly diminished.

However, this decision was reversed the next month after forces complained that the modified technology was producing a lower number of “useful lines of inquiry”. Internal records indicate the stricter setting cut the number of queries that yielded possible identifications from over half to a just 14%.

Severe Disparities

Although the Home Office and NPCC refused to say what threshold is currently used, the latest NPL study found the system could produce incorrect matches for women of Black heritage almost 100 times more frequently than for white women at certain settings.

The ministry commented on these findings: “Our evaluation identified that in a limited set of circumstances 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 accuracy setting, the police records state: “This adjustment significantly reduces the impact of bias across legally safeguarded attributes of ethnicity, generation and gender but had a significant negative impact on operational effectiveness”. The papers further note that police units complained that “a previously useful tool now delivered results of questionable value”.

Broader Rollout Plans

Meanwhile, the government has opened a two-and-a-half-month public review on its proposals to widen the use of facial recognition technology. Policing minister Sarah Jones has labeled the tool as the “most significant advance since genetic fingerprinting”.

Criticism from Advisors and Monitors

The chair of a police oversight board, head of the advisory panel for the national policing equality strategy, said: “There was scant consideration through equality strategy sessions of the technology deployment even with clear relevance with the plan’s concerns.

“These revelations show once again that the anti-racism commitments the police has undertaken through the race action plan are failing to be integrated into wider practice. Our reports have cautioned that innovative tools are being rolled out in a landscape where racial disparities, weak scrutiny and faulty information gathering continue to exist.

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

Home Office Response

A Home Office spokesperson stated: “The Home Office takes the conclusions of the report with utmost gravity and we have implemented changes. A new algorithm has been externally evaluated and procured, which has demonstrated no measurable discrimination. It will be tested early next year and will be subject to further assessment.

“The foremost aim is protecting the public. This revolutionary tool will assist officers to apprehend and prosecute offenders. There is human involvement in every step of the procedure and no further action would be pursued without specialist personnel meticulously examining the output.”