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Police forces across the United Kingdom effectively campaigned to deploy a facial recognition system known to be biased against females, young people, and individuals from ethnic minority groups, after complaining that a less biased version generated fewer investigative leads.

The Technology in Practice

British police utilize the national police database to carry out retrospective facial recognition searches. This process entails comparing a “probe image” of a suspect against a repository of over 19 million mugshots to identify possible hits.

Admitted Bias

The Home Office conceded last week that the technology was flawed. This acknowledgment followed a review by the government's National Physical Laboratory determined it misidentified people of Black and Asian heritage and females at much greater frequency than white men. The ministry stated it “took steps on the findings”.

“It prompts the question of whether this technology only becomes useful if users accept discrimination in race and sex. Operational ease is a weak argument for overriding fundamental rights.”

Known Issue

Official papers reveal that this bias has been known about for more than a year. 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 September 2024. The government-ordered NPL review found the system was had a higher probability to produce incorrect matches for photos of women, individuals of Black ethnicity, and those aged 40 and under.

A Policy U-Turn

In reaction, the national police leadership body mandated that the confidence threshold required for possible hits be raised to a point where the disparity was significantly reduced.

However, this directive was reversed the following month following complaints from police that the adjusted system was generating a lower number of “investigative leads”. Internal records indicate the higher threshold reduced the proportion of queries resulting in potential matches from 56% to a just 14%.

Profound Inequalities

Although the Home Office and NPCC declined to specify what threshold is currently used, the latest independent review discovered the system could generate incorrect matches for Black women almost 100 times more frequently than for Caucasian women at specific configurations.

The ministry stated on these findings: “Our evaluation identified that in a limited set of circumstances the software is more likely to wrongly flag some population segments 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: “The change significantly reduces the effect of bias across legally safeguarded attributes of race, age and sex but had a significant negative impact on operational effectiveness”. The documents add that police units argued that “a once effective tactic returned results of questionable value”.

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 the relevant minister has described the technology as the “most significant advance since DNA matching”.

Expert and Oversight Concerns

Abimbola Johnson, chair of the advisory panel for the police race action plan, said: “There was scant discussion through equality strategy sessions of the facial recognition rollout even with clear relevance with the plan’s concerns.

“This disclosure show once again that the anti-racism commitments policing has made via the race action plan are failing to be integrated into wider practice. Our reports have cautioned that new technologies are being implemented in a landscape where ethnic inequalities, weak scrutiny and poor data collection already persist.

“Any use of this technology must adhere to strict national standards, be subject to external review, and demonstrate it diminishes rather than compounds racial disparity.”

Home Office Response

A Home Office spokesperson stated: “We treat the findings of the study with utmost gravity and we have implemented changes. A updated software has been independently tested and procured, which has demonstrated no measurable discrimination. It will be tested 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 human involvement in each stage of the process and no further action would be pursued without trained officers carefully reviewing the output.”