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Law enforcement agencies across the United Kingdom effectively campaigned to deploy a face scanning system acknowledged as biased against females, youths, and members of ethnic minority groups, after complaining that a less biased version generated fewer potential suspects.

The Technology in Practice

British police utilize the police national database (PND) to conduct retrospective facial recognition searches. This process entails matching a “probe image” of a suspect against a repository of over 19 million custody photos to identify potential matches.

Acknowledged Discrimination

The UK interior ministry admitted last week that the technology was biased. This admission followed a study by the National Physical Laboratory (NPL) determined it misidentified 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 tolerate biases in race and gender. Operational ease is a weak argument for disregarding basic freedoms.”

Known Issue

Internal documents show that this bias has been recognized for over twelve months. Furthermore, law enforcement argued to overturn an earlier ruling that was intended to address the problem.

Senior officers were notified of the algorithmic discrimination in late 2024. The government-ordered NPL review concluded the system was more likely to suggest incorrect matches for photos of women, Black people, and those aged 40 and under.

A Policy U-Turn

In reaction, the National Police Chiefs’ Council (NPCC) mandated that the confidence threshold required for potential matches be raised to a level where the disparity was significantly reduced.

However, this directive was overturned the following month following complaints from police that the adjusted system was producing fewer “investigative leads”. Internal records show the higher threshold reduced the proportion of searches resulting in potential matches from over half to a mere under 15%.

Severe Disparities

Although the Home Office and NPCC declined to specify what threshold is now in operation, the recent NPL study discovered the system could produce false positives for women of Black heritage almost 100 times more often than for white women at specific configurations.

The ministry stated on these results: “Our evaluation identified that in a limited set of circumstances the software is more likely to wrongly flag some demographic groups in its search results.”

Balancing Utility and Fairness

Describing the effect of the brief increase to the system's accuracy setting, the NPCC documents state: “This adjustment greatly lessens the impact of bias across legally safeguarded attributes of race, age and gender but had a significant negative impact on operational effectiveness”. The documents further note that police units complained that “a once effective tactic returned results of questionable value”.

Wider Implementation Proposals

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

Expert and Oversight Concerns

Abimbola Johnson, chair of the advisory panel for the national policing equality strategy, commented: “There was very little consideration in race action plan meetings of the technology deployment even with obvious cross-over with the plan’s concerns.

“These revelations show yet again that the anti-racism commitments policing has made via the race action plan are not being translated into wider practice. Our reports have warned that new technologies are being rolled out in a context where ethnic inequalities, weak scrutiny and poor data collection already persist.

“All deployment of facial recognition must meet rigorous official guidelines, be subject to external review, and prove it diminishes rather than compounds ethnic bias.”

Official Statement

A Home Office spokesperson stated: “We takes the conclusions of the report seriously and we have implemented changes. A new algorithm has been independently tested and acquired, which has demonstrated no measurable discrimination. It will be trialled early next year and will be subject to further assessment.

“The foremost aim is protecting the public. This revolutionary tool will assist officers to put criminals and rapists behind bars. There is human involvement in every step of the procedure and no arrest or charge would be taken without specialist personnel carefully reviewing the results.”