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Law enforcement agencies across the United Kingdom successfully lobbied to deploy a face scanning system acknowledged as discriminatory against females, youths, and members of ethnic minority groups, following complaints that a less biased version generated fewer potential suspects.

The Technology in Practice

British police use the national police database to conduct retrospective facial recognition searches. This process entails comparing a reference photograph of a person of interest against a database of more than 19 million custody photos to find potential matches.

Admitted Bias

The Home Office conceded last week that the technology was flawed. This acknowledgment followed a review by the National Physical Laboratory (NPL) determined it incorrectly matched Black and Asian people and women at significantly higher rates than white men. The Home Office said it “took steps on the findings”.

“It prompts the question of whether this technology only becomes useful if users tolerate discrimination in race and gender. Convenience is a poor argument for overriding basic freedoms.”

Long-Standing Problem

Internal documents reveal that this bias has been known about for over twelve months. Furthermore, police forces argued to overturn an initial decision that was intended to address the problem.

Senior officers were informed of the system's bias in late 2024. The Home Office-commissioned laboratory study found the system was had a higher probability to produce false positives for images depicting females, individuals of Black ethnicity, and those aged 40 and under.

A Reversed Decision

In reaction, the national police leadership body mandated that the confidence threshold required for possible hits be raised to a point where the disparity was greatly diminished.

However, this decision was reversed the following month after forces complained that the modified technology was generating a lower number of “useful lines of inquiry”. NPCC documents show the stricter setting reduced the proportion of queries that yielded possible identifications from over half to a just 14%.

Profound Inequalities

Although the authorities declined to specify what threshold is now in operation, the recent independent review 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 results: “Our evaluation found that in a specific scenarios the algorithm is has a greater tendency to wrongly flag some population segments in its search results.”

Balancing Utility and Fairness

Outlining the impact of the temporary raise to the system's confidence threshold, the NPCC documents note: “This adjustment significantly reduces the effect of discrimination across legally safeguarded attributes of race, generation and gender but had a substantially detrimental effect on operational effectiveness”. The papers add that forces argued that “a once effective tactic now delivered results of limited benefit”.

Wider Implementation Proposals

Meanwhile, the UK administration has opened a ten-week consultation on its plans to expand the use of biometric scanning systems. Policing minister Sarah Jones has labeled the tool 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 discussion in race action plan meetings of the technology deployment even with clear relevance with the plan’s concerns.

“These revelations demonstrate yet again that the anti-racism commitments the police has undertaken through the equality initiative are not being translated 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 already persist.

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

Home Office Response

A Home Office spokesperson stated: “We takes the findings of the study with utmost gravity and we have implemented changes. A new algorithm has been independently tested and acquired, which has demonstrated no measurable discrimination. It will be trialled early next year and will be subject to further assessment.

“The foremost aim is protecting the public. This revolutionary tool will assist police to apprehend and prosecute offenders. There is human involvement in each stage of the procedure and no further action would be pursued without trained officers carefully reviewing the results.”