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

How the System Works

British police use the national police database to conduct retrospective facial recognition searches. This procedure entails matching a reference photograph of a suspect against a repository of more than 19 million custody photos to find potential matches.

Acknowledged Discrimination

The Home Office admitted last week that the technology was flawed. This acknowledgment followed a review by the government's National Physical Laboratory determined it incorrectly matched Black and Asian people and women at much greater frequency than Caucasian males. The Home Office stated it “had acted on the findings”.

“This raises the issue of whether facial recognition only becomes effective if users accept discrimination in race and sex. Convenience is a weak argument for overriding basic freedoms.”

Known Issue

Internal documents reveal that this discriminatory flaw has been recognized for more than a year. Furthermore, law enforcement lobbied to reverse an earlier ruling that was designed to mitigate the problem.

Police bosses were notified of the algorithmic discrimination in late 2024. The government-ordered NPL review found the system was had a higher probability to produce false positives for images depicting females, individuals of Black ethnicity, and those under 40 years old.

A Reversed Decision

In reaction, the national police leadership body mandated that the confidence threshold required for possible hits be raised to a point where the bias was greatly diminished.

However, this directive was overturned the following month after forces complained that the adjusted system was generating a lower number of “useful lines of inquiry”. Internal records indicate the higher threshold reduced the proportion of queries resulting in potential matches from 56% to a mere 14%.

Severe Disparities

Although the authorities refused to say what threshold is currently used, the recent NPL study discovered the system could produce false positives for Black women nearly a hundred times more often than for white women at certain settings.

The Home Office stated on these results: “Our evaluation identified that in a specific scenarios the algorithm 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 accuracy setting, the police records note: “The change significantly reduces the impact of discrimination across legally safeguarded attributes of race, generation and sex but had a substantially detrimental effect on operational effectiveness”. The papers further note that police units complained that “a once effective tactic returned results of questionable value”.

Wider Implementation Proposals

Meanwhile, the UK administration has opened a ten-week public review on its proposals to widen the use of biometric scanning systems. Policing minister the relevant minister has labeled the tool as the “most significant advance since genetic fingerprinting”.

Expert and Oversight Concerns

The chair of a police oversight board, chair of the advisory panel for the police race action plan, commented: “We observed scant discussion through equality strategy sessions of the technology deployment despite clear relevance with the strategy's goals.

“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 cautioned that new technologies are being rolled out in a landscape where racial disparities, weak scrutiny and faulty information gathering already persist.

“Any use of this technology must adhere to rigorous official guidelines, be subject to external review, and demonstrate it reduces rather than compounds racial disparity.”

Home Office Response

A government representative said: “The Home Office treat the conclusions of the study with utmost gravity and we have implemented changes. A updated software has been independently tested and procured, which has no statistically significant bias. It will be tested early next year and will be undergo further assessment.

“Our priority is protecting the public. This revolutionary tool will support officers to apprehend and prosecute offenders. There is officer review in every step of the process and no further action would be pursued without specialist personnel carefully reviewing the output.”