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Police forces across the United Kingdom 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 generated a reduced number of investigative leads.

The Technology in Practice

British police use the national police database to conduct searches using historical face recognition. This process entails comparing a “probe image” of a suspect against a repository of over 19 million custody photos to find possible hits.

Admitted Bias

The UK interior ministry conceded last week that the system was flawed. This admission came after a review by the government's National Physical Laboratory determined it misidentified Black and Asian people and females at much greater frequency than Caucasian males. The Home Office said it “had acted on the findings”.

“It prompts the issue of whether this technology only becomes effective if users tolerate biases in ethnicity and gender. Convenience is a weak argument for disregarding basic freedoms.”

Long-Standing Problem

Internal documents show that this bias has been recognized for over twelve months. Furthermore, police forces lobbied to reverse an initial decision that was intended to mitigate the problem.

Police bosses were informed of the system's bias in September 2024. The government-ordered laboratory study found the system was more likely to suggest incorrect matches for photos of females, Black people, and those aged 40 and under.

A Reversed Decision

In reaction, the National Police Chiefs’ Council (NPCC) mandated that the accuracy setting required for potential matches be raised to a point where the bias was significantly reduced.

However, this decision was reversed the following month following complaints from police that the modified technology was producing a lower number of “useful lines of inquiry”. NPCC documents indicate the higher threshold reduced the proportion of queries that yielded potential matches from 56% to a just 14%.

Profound Inequalities

Although the authorities declined to specify what threshold is now in operation, the recent independent review found the system could generate false positives for Black women almost 100 times more frequently than for white women at specific configurations.

The Home Office stated on these findings: “Our evaluation identified that in a specific scenarios the software is more likely to incorrectly include some population segments in its search results.”

Balancing Utility and Fairness

Describing the effect of the brief increase to the system's confidence threshold, the police records state: “The change greatly lessens the effect of discrimination across legally safeguarded attributes of race, age and gender but had a substantially detrimental effect on operational effectiveness”. The documents further note that forces complained that “a once effective tactic now delivered outcomes of limited benefit”.

Broader Rollout Plans

Meanwhile, the government has opened a two-and-a-half-month consultation on its plans to widen the use of biometric scanning systems. 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, head of the advisory panel for the police race action plan, commented: “There was very little discussion through race action plan meetings of the technology deployment even with obvious cross-over with the strategy's goals.

“This disclosure demonstrate once again that the anti-racism commitments policing has made through the equality initiative are failing to be integrated into wider practice. Our reports have warned that new technologies are being implemented in a landscape where ethnic inequalities, weak scrutiny and poor data collection continue to exist.

“All deployment of facial recognition must meet rigorous official guidelines, be independently scrutinised, and demonstrate it reduces rather than compounds racial disparity.”

Official Statement

A Home Office spokesperson stated: “We treat the conclusions of the study with utmost gravity and we have already taken action. A new algorithm has been externally evaluated and procured, which has demonstrated no measurable discrimination. It will be tested in the coming months and will be subject to evaluation.

“The foremost aim is ensuring public safety. This revolutionary tool will assist police to apprehend and prosecute offenders. There is human involvement in every step of the procedure and no further action would be taken without trained officers meticulously examining the output.”