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Police forces across the United Kingdom effectively campaigned to deploy a face scanning system acknowledged as biased against females, young people, and members of ethnic minority groups, after complaining that a less biased version produced a reduced number of potential suspects.

The Technology in Practice

British police use the national police database to carry out retrospective facial recognition searches. This process involves matching a “probe image” of a person of interest against a database of more than 19 million custody photos to find potential matches.

Admitted Bias

The Home Office admitted last week that the technology was biased. This admission came after a review by the National Physical Laboratory (NPL) found it incorrectly matched Black and Asian people and females at significantly higher rates than Caucasian males. The ministry said it “took steps on the findings”.

“This raises the issue of whether this technology only becomes effective if users accept biases in race and gender. Convenience is a weak argument for overriding fundamental rights.”

Known Issue

Official papers show that this discriminatory flaw has been recognized for over twelve months. Furthermore, police forces argued to overturn an earlier ruling that was intended to mitigate the problem.

Police bosses were informed of the system's bias in September 2024. The government-ordered NPL review concluded the system was more likely to suggest incorrect matches for images depicting women, individuals of Black ethnicity, and those under 40 years old.

A Reversed Decision

In response, the national police leadership body mandated that the accuracy setting required for potential matches be increased to a point where the bias was significantly reduced.

However, this directive was reversed the next month following complaints from police that the adjusted system was generating a lower number of “useful lines of inquiry”. Internal records indicate the higher threshold reduced the proportion of searches that yielded possible identifications from 56% to a mere under 15%.

Profound Inequalities

Although the Home Office and NPCC declined to specify what setting is currently used, the latest NPL study discovered the system could generate incorrect matches for women of Black heritage nearly a hundred times more frequently than for Caucasian women at specific configurations.

The Home Office commented on these results: “Our evaluation identified that in a limited set of circumstances the software is more likely to wrongly flag some demographic groups in its match reports.”

Operational Effectiveness vs. Bias

Describing the impact of the temporary raise to the system's accuracy setting, the NPCC documents note: “This adjustment greatly lessens the effect of discrimination across legally safeguarded attributes of race, age and gender but had a significant negative impact on police efficiency”. The documents further note that forces complained that “a previously useful tool returned outcomes of limited benefit”.

Wider Implementation Proposals

Meanwhile, the UK administration has opened a ten-week public review on its plans to expand the use of facial recognition technology. The minister for police Sarah Jones has labeled the technology 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 in equality strategy sessions of the facial recognition rollout even with obvious cross-over with the strategy's goals.

“This disclosure show 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 racial disparities, inadequate oversight and poor data collection already persist.

“Any use of this technology must meet rigorous official guidelines, be independently scrutinised, and demonstrate it reduces rather than compounds racial disparity.”

Home Office Response

A Home Office spokesperson stated: “The Home Office treat the findings of the report seriously and we have implemented changes. A new algorithm has been externally evaluated and acquired, which has no statistically significant bias. It will be trialled early next year and will be undergo further assessment.

“Our priority is ensuring public safety. This revolutionary tool will assist police to apprehend and prosecute offenders. There is officer review in every step of the process and no arrest or charge would be taken without specialist personnel meticulously examining the output.”