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Police forces across the United Kingdom effectively campaigned to deploy a facial recognition system known to be biased against women, young people, and individuals from minority ethnic backgrounds, after complaining that a more accurate version generated a reduced number of investigative leads.

How the System Works

UK forces utilize the national police database to conduct retrospective facial recognition searches. This procedure involves comparing a reference photograph of a person of interest against a repository of over 19 million custody photos to find potential matches.

Admitted Bias

The Home Office conceded last week that the system was flawed. This admission came after a study by the National Physical Laboratory (NPL) found it incorrectly matched Black and Asian people and females at significantly higher rates than white men. The Home Office said it “took steps on the findings”.

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

Long-Standing Problem

Official papers show that this bias has been known about for more than a year. Furthermore, police forces lobbied to reverse an initial decision that was intended to address the problem.

Police bosses were informed of the algorithmic discrimination in September 2024. The Home Office-commissioned NPL review found the system was more likely to produce incorrect matches for images depicting women, individuals of Black ethnicity, and those aged 40 and under.

A Policy U-Turn

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

However, this decision was overturned the following month after forces complained that the adjusted system was generating a lower number of “investigative leads”. NPCC documents show the stricter setting reduced the number of searches resulting in potential matches from over half to a mere 14%.

Profound Inequalities

Although the authorities declined to specify what threshold is currently used, the recent independent review found the system could produce false positives for women of Black heritage nearly a hundred times more frequently than for Caucasian women at specific configurations.

The Home Office stated on these findings: “The testing identified that in a limited set of circumstances the software is has a greater tendency to wrongly flag some demographic groups in its match reports.”

Balancing Utility and Fairness

Outlining the impact of the temporary raise to the system's confidence threshold, the police records note: “This adjustment significantly reduces the impact of discrimination across legally safeguarded attributes of ethnicity, age and sex but had a significant negative impact on police efficiency”. The papers further note that forces complained that “a once effective tactic returned results 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 described the tool 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, commented: “There was very little consideration in race action plan meetings of the facial recognition rollout even with clear relevance with the plan’s concerns.

“These revelations demonstrate yet again that the anti-racism commitments policing has undertaken through the equality initiative are failing to be integrated into wider practice. Independent assessments have warned that innovative tools are being implemented in a landscape where ethnic inequalities, inadequate oversight and poor data collection already persist.

“Any use of facial recognition must meet rigorous official guidelines, be subject to external review, and prove it diminishes rather than exacerbates racial disparity.”

Home Office Response

A government representative stated: “The Home Office treat the findings of the report with utmost gravity and we have already taken action. A updated software has been independently tested and procured, which has demonstrated no measurable discrimination. It will be trialled early next year and will be subject to further assessment.

“The foremost aim is ensuring public safety. This gamechanging technology will support police to put criminals and rapists behind bars. There is officer review in every step of the procedure and no arrest or charge would be taken without trained officers meticulously examining the results.”