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

The Technology in Practice

UK forces utilize the police national database (PND) to conduct retrospective facial recognition searches. This procedure involves matching a reference photograph of a person of interest against a repository of over 19 million mugshots to find potential matches.

Admitted Bias

The UK interior ministry admitted last week that the system was flawed. This acknowledgment came after a study by the government's National Physical Laboratory found it incorrectly matched Black and Asian people and women at much greater frequency than white men. The ministry stated it “had acted on the findings”.

“This raises the question of whether this technology only becomes useful if users tolerate biases in race and sex. Convenience is a weak argument for overriding fundamental rights.”

Long-Standing Problem

Official papers show that this discriminatory flaw has been known about for more than a year. Furthermore, police forces argued to overturn an initial decision that was designed to address the problem.

Senior officers were notified of the system's bias in September 2024. The government-ordered laboratory study found the system was more likely to produce incorrect matches for photos of females, individuals of Black ethnicity, and those aged 40 and under.

A Reversed Decision

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

However, this decision was overturned the following month after forces complained that the modified technology was producing a lower number of “useful lines of inquiry”. NPCC documents indicate the stricter setting cut the number of searches resulting in potential matches from 56% to a just 14%.

Profound Inequalities

Although the Home Office and NPCC refused to say what threshold is now in operation, the latest independent review discovered the system could generate false positives for Black women almost 100 times more often than for Caucasian women at specific configurations.

The ministry stated on these results: “The testing found that in a specific scenarios the algorithm is more likely to incorrectly include some demographic groups in its search results.”

Balancing Utility and Fairness

Outlining the effect of the temporary raise to the system's confidence threshold, the police records note: “The change significantly reduces the impact of discrimination across protected characteristics of ethnicity, age and gender but had a significant negative impact on police efficiency”. The papers further note that forces complained that “a once effective tactic returned results of limited benefit”.

Wider Implementation Proposals

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

Expert and Oversight Concerns

The chair of a police oversight board, head of the independent scrutiny and oversight board for the police race action plan, commented: “We observed very little consideration through race action plan meetings of the technology deployment even with clear relevance with the plan’s concerns.

“This disclosure demonstrate yet again that the anti-racism commitments the police has undertaken through the equality initiative are not being translated into broader operations. Independent assessments have warned that new technologies are being rolled out in a landscape where racial disparities, weak scrutiny and poor data collection continue to exist.

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

Home Office Response

A government representative said: “We treat the findings of the study seriously and we have implemented changes. A new algorithm has been independently tested and procured, which has demonstrated no measurable discrimination. It will be tested in the coming months and will be undergo further assessment.

“Our priority is protecting the public. This revolutionary tool will support officers to apprehend and prosecute offenders. There is human involvement in every step of the procedure and no arrest or charge would be pursued without specialist personnel carefully reviewing the output.”