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Police forces across the UK effectively campaigned to deploy a face scanning system acknowledged as biased against women, youths, and individuals from ethnic minority groups, after complaining that a more accurate version produced a reduced number of investigative leads.

How the System Works

UK forces utilize the national police database to conduct retrospective facial recognition searches. This process entails comparing a “probe image” of a suspect against a repository of more than 19 million mugshots to find potential matches.

Admitted Bias

The Home Office admitted last week that the system was flawed. This acknowledgment followed a study by the National Physical Laboratory (NPL) found it misidentified people of Black and Asian heritage and women at much greater frequency than white men. The Home Office said it “had acted on the findings”.

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

Known Issue

Official papers show that this bias has been known about for over twelve months. Furthermore, police forces lobbied to reverse an initial decision that was designed to mitigate the problem.

Police bosses were informed of the algorithmic discrimination in late 2024. The Home Office-commissioned NPL review concluded the system was had a higher probability to suggest false positives for photos of females, Black people, and those aged 40 and under.

A Policy U-Turn

In reaction, the national police leadership body mandated that the confidence threshold required for potential matches be raised to a level where the bias was significantly reduced.

However, this directive was reversed the following month following complaints from police that the adjusted system was producing a lower number of “useful lines of inquiry”. NPCC documents indicate the higher threshold reduced the number of queries resulting in possible identifications from 56% to a just under 15%.

Severe Disparities

Although the Home Office and NPCC refused to say what threshold is currently used, the latest independent review found the system could produce incorrect matches for women of Black heritage almost 100 times more frequently than for Caucasian women at specific configurations.

The ministry stated on these findings: “The testing identified that in a limited set of circumstances the software is has a greater tendency to wrongly flag some demographic groups in its search results.”

Balancing Utility and Fairness

Outlining the effect of the temporary raise to the system's accuracy setting, the NPCC documents note: “This adjustment greatly lessens the impact of discrimination across protected characteristics of ethnicity, generation and sex but had a significant negative impact on police efficiency”. The papers add that forces argued that “a once effective tactic now delivered results of questionable value”.

Wider Implementation Proposals

Meanwhile, the UK administration has launched a ten-week consultation on its proposals to widen the use of biometric scanning systems. Policing minister Sarah Jones has described the tool as the “most significant advance since genetic fingerprinting”.

Expert and Oversight Concerns

Abimbola Johnson, chair of the advisory panel for the national policing equality strategy, said: “There was very little discussion through race action plan meetings of the facial recognition rollout despite obvious cross-over with the strategy's goals.

“These revelations demonstrate yet again that the pledges to combat discrimination policing has made via the race action plan are not being translated into broader operations. Independent assessments have warned that new technologies are being implemented in a landscape where ethnic inequalities, weak scrutiny and poor data collection already persist.

“All deployment of facial recognition must adhere to strict national standards, be independently scrutinised, and prove it diminishes rather than exacerbates racial disparity.”

Official Statement

A Home Office spokesperson stated: “The Home Office treat the findings of the study seriously and we have already taken action. A new algorithm has been externally evaluated and acquired, which has demonstrated no measurable discrimination. It will be tested early next year and will be subject to evaluation.

“The foremost aim is ensuring public safety. This revolutionary tool will assist officers to put criminals and rapists behind bars. There is human involvement in each stage of the process and no further action would be pursued without specialist personnel carefully reviewing the results.”