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Law enforcement agencies across the UK effectively campaigned to deploy a face scanning system acknowledged as discriminatory against women, young people, and members of ethnic minority groups, following complaints that a more accurate version produced fewer investigative leads.

The Technology in Practice

British police utilize the police national database (PND) to carry out retrospective facial recognition searches. This procedure involves comparing a reference photograph of a suspect against a repository of over 19 million mugshots to identify potential matches.

Admitted Bias

The Home Office conceded last week that the technology was flawed. This acknowledgment followed a review by the National Physical Laboratory (NPL) determined it incorrectly matched people of Black and Asian heritage and women at significantly higher rates than white men. The ministry stated it “had acted on the findings”.

“This raises the issue of whether this technology only becomes effective if users accept discrimination in ethnicity and sex. Operational ease is a weak argument for overriding fundamental rights.”

Long-Standing Problem

Official papers show that this discriminatory flaw has been recognized for more than a year. Furthermore, law enforcement lobbied to reverse an initial decision that was intended to mitigate the problem.

Police bosses were notified of the algorithmic discrimination in September 2024. The government-ordered NPL review found the system was more likely to suggest incorrect matches for images depicting females, Black people, and those under 40 years old.

A Policy U-Turn

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

However, this directive was reversed the next month after forces complained that the modified technology was generating a lower number of “useful lines of inquiry”. Internal records indicate the stricter setting cut the proportion of searches that yielded potential matches from over half to a mere 14%.

Severe Disparities

Although the Home Office and NPCC declined to specify what setting is currently used, the latest independent review found the system could generate false positives for women of Black heritage nearly a hundred times more often than for white women at specific configurations.

The Home Office stated on these findings: “The testing identified that in a specific scenarios the algorithm is has a greater tendency to wrongly flag some population segments in its match reports.”

Balancing Utility and Fairness

Outlining the impact of the brief increase to the system's accuracy setting, the NPCC documents state: “The change greatly lessens the impact of discrimination across protected characteristics of ethnicity, age and gender but had a substantially detrimental effect on operational effectiveness”. The papers further note that police units argued that “a once effective tactic returned outcomes of questionable value”.

Wider Implementation Proposals

Meanwhile, the UK administration has launched a two-and-a-half-month public review on its proposals to widen the use of biometric scanning systems. Policing minister Sarah Jones has described the tool as the “most significant advance since DNA matching”.

Criticism from Advisors and Monitors

Abimbola Johnson, chair of the independent scrutiny and oversight board for the national policing equality strategy, commented: “We observed very little discussion in equality strategy sessions of the technology deployment even with obvious cross-over with the plan’s concerns.

“This disclosure demonstrate once again that the pledges to combat discrimination the police has made through the equality initiative are not being translated into wider practice. Independent assessments 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 this technology must meet rigorous official guidelines, be subject to external review, and demonstrate it diminishes rather than exacerbates ethnic bias.”

Home Office Response

A Home Office spokesperson stated: “The Home Office treat the findings of the report with utmost gravity and we have implemented changes. A updated software has been independently tested and acquired, which has demonstrated no measurable discrimination. It will be trialled in the coming months and will be subject to further assessment.

“Our priority is protecting the public. This gamechanging technology will assist officers to put criminals and rapists behind bars. There is officer review in each stage of the procedure and no further action would be pursued without specialist personnel meticulously examining the results.”