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Police forces across the UK successfully lobbied to use a face scanning system known to be discriminatory against females, young people, and members of minority ethnic backgrounds, after complaining that a less biased version produced a reduced number of potential suspects.

The Technology in Practice

British police utilize the national police database to carry out retrospective facial recognition searches. This procedure involves matching a reference photograph of a suspect against a database of over 19 million mugshots to find potential matches.

Admitted Bias

The Home Office conceded last week that the system was biased. This acknowledgment followed a review by the government's National Physical Laboratory found it incorrectly matched 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 question of whether facial recognition only becomes useful if users accept biases in race and sex. Operational ease is a weak argument for overriding fundamental rights.”

Long-Standing Problem

Official papers reveal that this bias has been recognized for more than a year. Furthermore, police forces lobbied to reverse an initial decision that was designed to mitigate the problem.

Senior officers were notified of the algorithmic discrimination in late 2024. The government-ordered NPL review found the system was had a higher probability to suggest incorrect matches for photos of women, Black people, and those under 40 years old.

A Reversed Decision

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

However, this decision was reversed the following month following complaints from police that the adjusted system was producing a lower number of “useful lines of inquiry”. Internal records show the stricter setting reduced the number of queries resulting in possible identifications from 56% to a mere 14%.

Profound Inequalities

Although the authorities refused to say what threshold is currently used, the latest NPL study found the system could generate false positives for women of Black heritage almost 100 times more frequently than for Caucasian women at certain settings.

The Home Office stated on these results: “The testing found that in a limited set of circumstances the algorithm is more likely to incorrectly include some demographic groups in its search results.”

Operational Effectiveness vs. Bias

Describing the impact of the temporary raise to the system's accuracy setting, the police records note: “The change significantly reduces the impact of discrimination across protected characteristics of race, age and gender but had a substantially detrimental effect on operational effectiveness”. The documents further note that police units complained that “a once effective tactic now delivered outcomes of limited benefit”.

Wider Implementation Proposals

Meanwhile, the government has opened a ten-week public review on its proposals to expand the use of biometric scanning systems. Policing minister Sarah Jones has labeled the tool as the “biggest breakthrough since genetic fingerprinting”.

Criticism from Advisors and Monitors

The chair of a police oversight board, head of the independent scrutiny and oversight board for the police race action plan, said: “There was very little consideration in race action plan meetings of the technology deployment even with obvious cross-over with the strategy's goals.

“This disclosure show once again that the anti-racism commitments the police has undertaken through the race action plan are failing to be integrated into wider practice. Independent assessments have warned that new technologies are being implemented in a context where racial disparities, inadequate oversight and poor data collection continue to exist.

“Any use of this technology must adhere to rigorous official guidelines, be independently scrutinised, and prove it reduces rather than exacerbates ethnic bias.”

Home Office Response

A Home Office spokesperson said: “We takes the conclusions of the study with utmost gravity and we have implemented changes. A new algorithm has been independently tested and procured, which has demonstrated no measurable discrimination. It will be tested early next year and will be subject to evaluation.

“The foremost aim is protecting the public. This revolutionary tool will support police to apprehend and prosecute offenders. There is officer review in each stage of the process and no arrest or charge would be pursued without trained officers meticulously examining the results.”