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Police forces across the UK effectively campaigned to use a facial recognition system acknowledged as biased against women, youths, and members of ethnic minority groups, following complaints that a less biased version generated a reduced number of investigative leads.

The Technology in Practice

British police use the police national database (PND) to carry out searches using historical face recognition. This procedure involves comparing a “probe image” of a suspect against a repository of more than 19 million mugshots to find potential matches.

Acknowledged Discrimination

The Home Office conceded last week that the technology was flawed. This acknowledgment came after a study by the government's National Physical Laboratory determined it incorrectly matched Black and Asian people and women at significantly higher rates than Caucasian males. The ministry said it “had acted on the findings”.

“This raises the question of whether this technology only becomes useful if users tolerate discrimination in race and sex. Convenience is a poor argument for disregarding fundamental rights.”

Long-Standing Problem

Internal documents reveal that this discriminatory flaw has been recognized for more than a year. Furthermore, police forces argued to overturn an initial decision that was intended to mitigate the problem.

Police bosses were notified of the algorithmic discrimination in late 2024. The government-ordered laboratory study found the system was more likely to produce incorrect matches for photos of women, individuals of Black ethnicity, and those under 40 years old.

A Reversed Decision

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

However, this decision was reversed the next month after forces complained that the adjusted system was generating fewer “investigative leads”. Internal records show the stricter setting reduced the number of queries that yielded potential matches from 56% to a mere 14%.

Profound Inequalities

Although the authorities refused to say what threshold is currently used, the latest independent review found the system could generate false positives for women of Black heritage almost 100 times more often than for Caucasian women at specific configurations.

The ministry stated on these findings: “Our evaluation identified that in a specific scenarios the algorithm is has a greater tendency to wrongly flag some demographic groups in its search results.”

Operational Effectiveness vs. Bias

Describing the impact of the temporary raise to the system's confidence threshold, the police records note: “The change greatly lessens the effect of discrimination across protected characteristics of ethnicity, generation and gender but had a substantially detrimental effect on police efficiency”. The papers further note that police units argued that “a once effective tactic returned outcomes of questionable value”.

Broader Rollout Plans

Meanwhile, the UK administration has opened a two-and-a-half-month public review on its plans to widen the use of facial recognition technology. Policing minister the relevant minister has labeled the tool as the “biggest breakthrough since DNA matching”.

Criticism from Advisors and Monitors

Abimbola Johnson, head of the independent scrutiny and oversight board for the police race action plan, said: “There was very little consideration through race action plan meetings of the technology deployment despite obvious cross-over with the plan’s concerns.

“This disclosure show yet again that the anti-racism commitments the police has undertaken via the race action plan are not being translated into broader operations. Independent assessments have cautioned that innovative tools are being rolled out in a landscape where racial disparities, weak scrutiny and poor data collection already persist.

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

Official Statement

A government representative said: “The Home Office treat the findings of the report with utmost gravity and we have already taken action. A new algorithm has been externally evaluated and acquired, which has demonstrated no measurable discrimination. It will be tested early next year and will be undergo further assessment.

“The foremost aim is ensuring public safety. This revolutionary tool will assist officers to put criminals and rapists behind bars. There is human involvement in every step of the process and no arrest or charge would be taken without trained officers meticulously examining the output.”