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Law enforcement agencies across the UK effectively campaigned to deploy a face scanning system known to be biased against women, young people, and individuals from minority ethnic backgrounds, following complaints that a more accurate version produced a reduced number of potential suspects.

How the System Works

UK forces use the national police database to carry out retrospective facial recognition searches. This procedure entails comparing a “probe image” of a suspect against a repository of more than 19 million custody photos to find potential matches.

Acknowledged Discrimination

The Home Office conceded last week that the technology was flawed. This acknowledgment followed a study by the National Physical Laboratory (NPL) determined it incorrectly matched Black and Asian people and females at much greater frequency than Caucasian males. The ministry said it “had acted on the findings”.

“This raises the issue of whether facial recognition only becomes effective if users accept biases in race and gender. Convenience is a poor argument for disregarding fundamental rights.”

Long-Standing Problem

Internal documents show that this discriminatory flaw has been recognized for over twelve months. Furthermore, law enforcement lobbied to reverse an initial decision that was intended to address the problem.

Senior officers were notified of the algorithmic discrimination in late 2024. The Home Office-commissioned NPL review found the system was had a higher probability to produce incorrect matches for images depicting women, individuals of Black ethnicity, and those under 40 years old.

A Reversed Decision

In reaction, the national police leadership body ordered that the accuracy setting required for potential matches be increased to a level where the disparity was significantly reduced.

However, this decision was overturned the following month after forces complained that the adjusted system was producing a lower number of “useful lines of inquiry”. NPCC documents show the higher threshold cut the proportion of queries that yielded possible identifications from over half to a mere under 15%.

Severe Disparities

Although the authorities refused to say what threshold is now in operation, the recent NPL study found the system could generate incorrect matches for women of Black heritage nearly a hundred times more frequently than for Caucasian women at specific configurations.

The ministry stated on these results: “Our evaluation found that in a specific scenarios the algorithm is more likely to incorrectly include some population segments in its match reports.”

Balancing Utility and Fairness

Describing the impact of the brief increase to the system's confidence threshold, the NPCC documents note: “The change greatly lessens the effect of bias across legally safeguarded attributes of ethnicity, generation and gender but had a substantially detrimental effect on operational effectiveness”. The papers further note that police units complained that “a previously useful tool returned results of questionable value”.

Broader Rollout Plans

Meanwhile, the government has opened a ten-week consultation on its plans to expand the use of facial recognition technology. Policing minister Sarah Jones has described the tool as the “most significant advance since genetic fingerprinting”.

Criticism from Advisors and Monitors

The chair of a police oversight board, head of the advisory panel for the national policing equality strategy, commented: “We observed scant discussion through race action plan meetings of the technology deployment even with obvious cross-over 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 broader operations. Independent assessments have cautioned that new technologies are being rolled out in a context where ethnic inequalities, weak scrutiny and faulty information gathering already persist.

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

Home Office Response

A government representative stated: “We takes the findings of the report seriously and we have implemented changes. A new algorithm has been externally evaluated and acquired, which has demonstrated no measurable discrimination. It will be tested in the coming months and will be undergo further assessment.

“Our priority is protecting the public. This revolutionary tool will assist police to apprehend and prosecute offenders. There is officer review in each stage of the process and no further action would be pursued without trained officers meticulously examining the output.”