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Police forces across the UK effectively campaigned to deploy a face scanning system known to be biased against females, youths, and individuals from ethnic minority groups, after complaining that a more accurate version produced fewer potential suspects.

The Technology in Practice

British police utilize the national police database to conduct retrospective facial recognition searches. This procedure involves comparing a “probe image” of a suspect against a repository of more than 19 million custody photos to identify potential matches.

Admitted Bias

The Home Office admitted last week that the technology was biased. This admission followed a review by the government's National Physical Laboratory found it incorrectly matched Black and Asian people and females at much greater frequency than Caucasian males. The Home Office said it “took steps on the findings”.

“This raises the issue of whether this technology only becomes useful if users accept discrimination in ethnicity and sex. Operational ease is a weak argument for overriding basic freedoms.”

Long-Standing Problem

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

Senior officers were notified of the algorithmic discrimination in September 2024. The Home Office-commissioned NPL review found the system was had a higher probability to produce false positives for images depicting women, individuals of Black ethnicity, and those aged 40 and under.

A Reversed Decision

In reaction, the national police leadership body ordered that the confidence threshold required for potential matches be increased to a point where the bias was greatly diminished.

However, this decision was overturned the following month after forces complained that the adjusted system was producing fewer “useful lines of inquiry”. Internal records show the stricter setting cut the number of queries resulting in potential matches from over half to a just 14%.

Severe Disparities

Although the authorities refused to say what setting is currently used, the latest independent review found the system could produce incorrect matches for Black women almost 100 times more frequently than for white women at specific configurations.

The ministry stated on these results: “The testing found that in a limited set of circumstances the algorithm is more likely to wrongly flag some population segments in its match reports.”

Balancing Utility and Fairness

Outlining the effect of the temporary raise to the system's confidence threshold, the police records note: “This adjustment greatly lessens the effect of discrimination across protected characteristics of race, age and sex but had a substantially detrimental effect on police efficiency”. The documents add that police units argued that “a previously useful tool returned results of questionable value”.

Broader Rollout Plans

Meanwhile, the government has opened a ten-week public review on its proposals to expand the use of facial recognition technology. Policing minister Sarah Jones has described the tool as the “most significant advance since DNA matching”.

Expert and Oversight Concerns

Abimbola Johnson, chair of the independent scrutiny and oversight board for the police race action plan, said: “There was very little consideration through race action plan meetings of the technology deployment even with clear relevance with the plan’s concerns.

“This disclosure demonstrate once again that the anti-racism commitments policing has made through the equality initiative are failing to be integrated into broader operations. Our reports have cautioned that new technologies are being implemented in a context where ethnic inequalities, inadequate oversight and poor data collection continue to exist.

“All deployment of facial recognition must adhere to strict national standards, be subject to external review, and prove it reduces rather than exacerbates racial disparity.”

Home Office Response

A Home Office spokesperson said: “The Home Office treat the conclusions of the report seriously and we have already taken action. A new algorithm has been externally evaluated and acquired, which has no statistically significant bias. It will be tested in the coming months and will be undergo evaluation.

“Our priority is protecting the public. This revolutionary tool will support officers to put criminals and rapists behind bars. There is human involvement in each stage of the procedure and no arrest or charge would be taken without specialist personnel carefully reviewing the results.”