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Law enforcement agencies across the UK successfully lobbied to use a face scanning system known to be discriminatory against females, youths, and individuals from ethnic minority groups, following complaints that a less biased version produced a reduced number of investigative leads.

The Technology in Practice

UK forces use the police national database (PND) to carry out retrospective facial recognition searches. This process involves matching a “probe image” of a person of interest against a repository of over 19 million mugshots to identify potential matches.

Acknowledged Discrimination

The Home Office admitted last week that the technology was biased. This acknowledgment came after a study by the National Physical Laboratory (NPL) determined it misidentified Black and Asian people and females at significantly higher rates than Caucasian males. The ministry stated it “had acted on the findings”.

“It prompts the question of whether facial recognition only becomes effective if users tolerate biases in race and gender. Convenience is a poor argument for disregarding basic freedoms.”

Known Issue

Internal documents reveal that this discriminatory flaw has been known about for over twelve months. Furthermore, police forces lobbied to reverse an earlier ruling that was intended to address the problem.

Senior officers were notified of the system's bias in September 2024. The government-ordered laboratory study found the system was had a higher probability to suggest incorrect matches for images depicting females, individuals of Black ethnicity, and those under 40 years old.

A Policy U-Turn

In reaction, the National Police Chiefs’ Council (NPCC) mandated that the accuracy setting required for possible hits be increased to a level where the bias was greatly diminished.

However, this directive was reversed the following month after forces complained that the adjusted system was producing a lower number of “useful lines of inquiry”. NPCC documents indicate the stricter setting cut the number of searches that yielded possible identifications from 56% to a just 14%.

Profound Inequalities

Although the Home Office and NPCC refused to say what threshold is currently used, the recent independent review discovered the system could produce false positives for Black women almost 100 times more often than for Caucasian women at specific configurations.

The Home Office stated on these results: “Our evaluation identified that in a specific scenarios the algorithm is more likely to wrongly flag some demographic groups in its match reports.”

Balancing Utility and Fairness

Describing the impact of the brief increase to the system's confidence threshold, the police records note: “This adjustment greatly lessens the impact of discrimination across protected characteristics of race, generation and sex but had a significant negative impact on operational effectiveness”. The papers further note that forces argued that “a previously useful tool now delivered results of limited benefit”.

Wider Implementation Proposals

Meanwhile, the UK administration has launched a ten-week consultation on its plans to expand the use of biometric scanning systems. The minister for police Sarah Jones has described the technology as the “most significant advance since DNA matching”.

Expert and Oversight Concerns

Abimbola Johnson, head of the advisory panel for the national policing equality strategy, said: “There was scant consideration through race action plan meetings of the facial recognition rollout even with obvious cross-over with the plan’s concerns.

“This disclosure show once again that the anti-racism commitments policing has undertaken through the race action plan are not being translated into wider practice. Our reports have warned that new technologies are being implemented in a landscape where racial disparities, weak scrutiny and faulty information gathering already persist.

“Any use of facial recognition must meet strict national standards, be subject to external review, and demonstrate it diminishes rather than exacerbates ethnic bias.”

Home Office Response

A Home Office spokesperson said: “The Home Office takes the findings of the study seriously and we have implemented changes. A updated software has been independently tested and acquired, which has demonstrated no measurable discrimination. It will be trialled in the coming months and will be subject to evaluation.

“Our priority is ensuring public safety. This gamechanging technology will assist police to put criminals and rapists behind bars. There is officer review in every step of the process and no further action would be taken without specialist personnel carefully reviewing the results.”