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Police forces across the United Kingdom successfully lobbied to deploy a face scanning system known to be biased against females, young people, and members of ethnic minority groups, after complaining that a more accurate version produced fewer investigative leads.

How the System Works

UK forces utilize the police national database (PND) to conduct retrospective facial recognition searches. This procedure entails comparing a reference photograph of a person of interest against a repository of over 19 million mugshots to identify potential matches.

Admitted Bias

The Home Office conceded last week that the system was biased. This acknowledgment came after a study by the government's National Physical Laboratory found it incorrectly matched Black and Asian people and women at significantly higher rates than white men. The Home Office said it “had acted on the findings”.

“It prompts the issue of whether facial recognition only becomes useful if users tolerate biases in ethnicity and gender. Convenience is a weak argument for disregarding fundamental rights.”

Known Issue

Internal documents reveal that this discriminatory flaw has been known about for more than a year. Furthermore, law enforcement argued to overturn an initial decision that was designed to address the problem.

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

A Policy U-Turn

In response, the national police leadership body mandated that the accuracy setting required for possible hits be raised to a level where the disparity was greatly diminished.

However, this decision was overturned the next month following complaints from police that the adjusted system was generating fewer “investigative leads”. NPCC documents show the higher threshold reduced the number of queries resulting in possible identifications from 56% to a just 14%.

Severe Disparities

Although the authorities refused to say what threshold is now in operation, the recent independent review discovered the system could produce incorrect matches for women of Black heritage nearly a hundred times more frequently than for Caucasian women at certain settings.

The ministry stated on these results: “Our evaluation found that in a limited set of circumstances the algorithm is has a greater tendency to wrongly flag some population segments in its search results.”

Balancing Utility and Fairness

Outlining the impact of the brief increase to the system's confidence threshold, the NPCC documents state: “The change greatly lessens the impact of discrimination across protected characteristics of ethnicity, generation and sex but had a significant negative impact on police efficiency”. The documents add that forces complained that “a once effective tactic returned outcomes of limited benefit”.

Wider Implementation Proposals

Meanwhile, the government has launched a ten-week consultation on its plans to widen the use of biometric scanning systems. The minister for police the relevant minister has described the technology as the “most significant advance since genetic fingerprinting”.

Expert and Oversight Concerns

The chair of a police oversight board, chair of the independent scrutiny and oversight board for the national policing equality strategy, commented: “There was scant discussion in race action plan meetings of the facial recognition rollout despite clear relevance with the strategy's goals.

“These revelations show yet again that the anti-racism commitments policing has undertaken via the equality initiative are failing to be integrated into wider practice. Our reports have cautioned that innovative tools are being rolled out in a landscape where racial disparities, inadequate oversight and faulty information gathering already persist.

“All deployment of this technology must adhere to rigorous official guidelines, be independently scrutinised, and demonstrate it reduces rather than exacerbates racial disparity.”

Official Statement

A government representative said: “The Home Office treat the conclusions of the study 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 subject to evaluation.

“The foremost aim is ensuring public safety. This revolutionary tool will support police to apprehend and prosecute offenders. There is human involvement in every step of the process and no arrest or charge would be pursued without specialist personnel carefully reviewing the output.”