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Police forces across the UK successfully lobbied to use a facial recognition system known to be biased against women, young people, and members of ethnic minority groups, following complaints that a less biased version generated 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 entails matching a reference photograph of a person of interest against a database of over 19 million custody photos to identify potential matches.

Admitted Bias

The UK interior ministry admitted last week that the system was biased. This admission came after a study by the government's National Physical Laboratory determined it incorrectly matched Black and Asian people and females at significantly higher rates than white men. The ministry said it “had acted on the findings”.

“It prompts 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.”

Long-Standing Problem

Official papers 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 September 2024. The government-ordered laboratory study concluded the system was had a higher probability to produce false positives for photos of women, individuals of Black ethnicity, and those aged 40 and under.

A Reversed Decision

In response, the national police leadership body ordered that the confidence threshold required for possible hits be raised to a level where the bias was significantly reduced.

However, this decision was reversed the following month after forces complained that the adjusted system was generating a lower number of “investigative leads”. NPCC documents indicate the stricter setting reduced the number of queries that yielded potential matches from over half to a mere under 15%.

Profound Inequalities

Although the authorities declined to specify what threshold is currently used, the recent independent review discovered the system could produce incorrect matches for women of Black heritage almost 100 times more frequently than for white women at specific configurations.

The Home Office commented on these findings: “Our evaluation identified that in a specific scenarios the software 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 NPCC documents note: “The change greatly lessens the effect of discrimination across protected characteristics of ethnicity, generation and gender but had a substantially detrimental effect on operational effectiveness”. The papers add that forces complained that “a previously useful tool now delivered results of limited benefit”.

Wider Implementation Proposals

Meanwhile, the UK administration has opened a two-and-a-half-month public review on its proposals to expand the use of biometric scanning systems. Policing minister Sarah Jones has labeled the technology as the “biggest breakthrough since genetic fingerprinting”.

Criticism from Advisors and Monitors

The chair of a police oversight board, chair of the advisory panel for the national policing equality strategy, said: “We observed very little consideration through equality strategy sessions of the facial recognition rollout even with clear relevance with the plan’s concerns.

“These revelations show yet again that the pledges to combat discrimination the police has made through the race action plan are not being translated into broader operations. Independent assessments have cautioned that innovative tools are being rolled out in a landscape where ethnic inequalities, 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 prove it reduces rather than exacerbates racial disparity.”

Official Statement

A government representative stated: “The Home Office takes the findings of the report seriously and we have implemented changes. A new algorithm has been externally evaluated and procured, which has no statistically significant bias. It will be trialled in the coming months and will be subject to further assessment.

“The foremost aim is protecting the public. This revolutionary tool will support officers to put criminals and rapists behind bars. There is officer review in each stage of the procedure and no arrest or charge would be taken without trained officers meticulously examining the results.”