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Police forces across the United Kingdom successfully lobbied to use a face scanning system known to be biased against women, young people, and members of ethnic minority groups, following complaints that a more accurate version produced fewer potential suspects.

The Technology in Practice

British police utilize the national police database to conduct searches using historical face recognition. This procedure involves matching a “probe image” of a suspect against a repository of over 19 million mugshots to find potential matches.

Acknowledged Discrimination

The Home Office admitted last week that the technology was biased. This admission came after a study by the government's National Physical Laboratory determined it incorrectly matched people of Black and Asian heritage and women at significantly higher rates than Caucasian males. The ministry said it “had acted on the findings”.

“This raises the question of whether facial recognition only becomes effective if users tolerate biases in race and sex. Operational ease is a poor argument for disregarding basic freedoms.”

Known Issue

Official papers reveal that this bias has been known about for over twelve months. Furthermore, law enforcement argued to overturn an earlier ruling that was intended to mitigate the problem.

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

A Reversed Decision

In response, the National Police Chiefs’ Council (NPCC) ordered that the accuracy setting required for possible hits be increased to a level where the bias was significantly reduced.

However, this directive was overturned the next month following complaints from police that the modified technology was generating fewer “useful lines of inquiry”. Internal records show the stricter setting reduced the proportion of queries that yielded possible identifications from 56% to a just under 15%.

Profound Inequalities

Although the authorities declined to specify what setting is now in operation, the recent independent review found the system could produce incorrect matches for women of Black heritage nearly a hundred times more often than for white women at certain settings.

The ministry commented on these findings: “The testing identified that in a limited set of circumstances the software is more likely to incorrectly include some demographic groups in its match reports.”

Balancing Utility and Fairness

Outlining the effect of the temporary raise to the system's accuracy setting, the police records note: “The change greatly lessens the effect of bias across protected characteristics of race, age and sex but had a substantially detrimental effect on operational effectiveness”. The documents further note that forces argued that “a once effective tactic returned outcomes of questionable value”.

Wider Implementation Proposals

Meanwhile, the UK administration has opened a ten-week consultation on its proposals to widen the use of facial recognition technology. The minister for police Sarah Jones has described the tool as the “most significant advance since genetic fingerprinting”.

Criticism from Advisors and Monitors

The chair of a police oversight board, chair of the advisory panel for the police race action plan, commented: “There was scant consideration in race action plan meetings of the technology deployment despite obvious cross-over with the plan’s concerns.

“This disclosure demonstrate yet again that the anti-racism commitments the police has made via the race action plan are not being translated into broader operations. Independent assessments have warned that new technologies are being rolled out in a context where ethnic inequalities, inadequate oversight and poor data collection already persist.

“All deployment of this technology must meet rigorous official guidelines, be independently scrutinised, and demonstrate it diminishes rather than compounds ethnic bias.”

Home Office Response

A Home Office spokesperson stated: “We takes the conclusions of the study with utmost gravity and we have implemented changes. A new algorithm has been independently tested and acquired, which has no statistically significant bias. It will be trialled in the coming months and will be undergo evaluation.

“The foremost aim is ensuring public safety. This gamechanging technology will support officers to put criminals and rapists behind bars. There is human involvement in each stage of the process and no further action would be taken without trained officers meticulously examining the output.”