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Law enforcement agencies across the UK effectively campaigned to deploy a face scanning system known to be discriminatory against women, youths, and individuals from minority ethnic backgrounds, after complaining that a more accurate version generated fewer investigative leads.

How the System Works

British police use the police national database (PND) to conduct searches using historical face recognition. This procedure entails comparing a reference photograph of a suspect against a database of over 19 million custody photos to identify potential matches.

Admitted Bias

The Home Office admitted last week that the system was biased. This acknowledgment followed a review by the government's National Physical Laboratory determined it misidentified people of Black and Asian heritage and women at significantly higher rates than white men. The Home Office said it “took steps on the findings”.

“This raises the issue of whether facial recognition only becomes effective if users tolerate discrimination in race and gender. Convenience is a weak argument for overriding fundamental rights.”

Known Issue

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

Police bosses were informed of the system's bias in late 2024. The government-ordered NPL review concluded the system was had a higher probability to suggest incorrect matches for photos of women, Black people, and those aged 40 and under.

A Reversed Decision

In response, the national police leadership body mandated that the accuracy setting required for potential matches be raised to a level where the disparity was greatly diminished.

However, this decision was overturned the following month following complaints from police that the modified technology was generating a lower number of “useful lines of inquiry”. NPCC documents indicate the stricter setting cut the number of queries resulting in possible identifications from over half to a just 14%.

Profound Inequalities

Although the authorities refused to say what threshold is currently used, the recent NPL study found the system could produce false positives for women of Black heritage almost 100 times more often than for Caucasian women at specific configurations.

The ministry commented on these findings: “Our evaluation identified that in a specific scenarios the algorithm is has a greater tendency 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 state: “This adjustment significantly reduces the impact of discrimination across legally safeguarded attributes of ethnicity, age and sex but had a significant negative impact on police efficiency”. The documents further note that police units complained that “a previously useful tool returned results of limited benefit”.

Wider Implementation Proposals

Meanwhile, the UK administration has opened a two-and-a-half-month consultation on its proposals to widen the use of facial recognition technology. The minister for police the relevant minister has described the technology as the “biggest breakthrough since genetic fingerprinting”.

Criticism from Advisors and Monitors

Abimbola Johnson, head of the independent scrutiny and oversight board for the police race action plan, commented: “There was scant discussion in equality strategy sessions of the facial recognition rollout despite clear relevance with the strategy's goals.

“This disclosure show yet again that the pledges to combat discrimination policing has made via the equality initiative are failing to be integrated into wider practice. Our reports have cautioned that new technologies are being rolled out in a landscape where racial disparities, weak scrutiny and faulty information gathering already persist.

“All deployment of facial recognition must adhere to strict national standards, be subject to external review, and demonstrate it reduces rather than compounds ethnic bias.”

Home Office Response

A government representative said: “The Home Office takes the findings of the study with utmost gravity and we have already taken action. A updated software has been independently tested and procured, which has no statistically significant bias. It will be trialled early next year and will be undergo further assessment.

“The foremost aim is ensuring public safety. This revolutionary tool will assist police to apprehend and prosecute offenders. There is officer review in each stage of the procedure and no further action would be taken without trained officers carefully reviewing the output.”