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Law enforcement agencies across the United Kingdom successfully lobbied to deploy a facial recognition system known to be biased against females, youths, and individuals from ethnic minority groups, following complaints that a less biased version generated fewer investigative leads.

How the System Works

British police utilize the police national database (PND) to conduct retrospective facial recognition searches. This procedure entails comparing a “probe image” 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 technology was biased. This acknowledgment came after a review by the government's National Physical Laboratory found it misidentified Black and Asian people and females at much greater frequency than Caucasian males. The ministry stated it “had acted on the findings”.

“It prompts the issue of whether facial recognition only becomes effective if users accept discrimination in race and sex. Operational ease is a weak argument for overriding fundamental rights.”

Long-Standing Problem

Official papers reveal that this bias has been known about for more than a year. Furthermore, law enforcement argued to overturn an earlier ruling that was designed to mitigate 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 suggest incorrect matches for photos of females, Black people, and those under 40 years old.

A Policy U-Turn

In response, the national police leadership body mandated that the confidence threshold required for possible hits be increased to a level where the bias was significantly reduced.

However, this decision was overturned the next month following complaints from police that the modified technology was generating a lower number of “useful lines of inquiry”. NPCC documents show the higher threshold cut the number of searches resulting in potential matches from 56% to a just 14%.

Severe Disparities

Although the authorities declined to specify what threshold is now in operation, the recent NPL study discovered the system could produce incorrect matches for Black women almost 100 times more often than for Caucasian women at specific configurations.

The Home Office stated on these findings: “Our evaluation found that in a specific scenarios the software is more likely 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 accuracy setting, the NPCC documents state: “This adjustment greatly lessens the impact of bias across legally safeguarded attributes of race, generation and sex but had a significant negative impact on operational effectiveness”. The documents add that forces complained that “a once effective tactic now delivered results of questionable value”.

Broader Rollout Plans

Meanwhile, the UK administration has launched a ten-week public review on its proposals to widen the use of biometric scanning systems. The minister for police the relevant minister has described the tool as the “biggest breakthrough since genetic fingerprinting”.

Criticism from Advisors and Monitors

Abimbola Johnson, chair of the independent scrutiny and oversight board for the national policing equality strategy, said: “We observed scant discussion through equality strategy sessions of the technology deployment despite clear relevance with the plan’s concerns.

“These revelations demonstrate once again that the anti-racism commitments policing has made via the race action plan are failing to be integrated into broader operations. Independent assessments have cautioned that new technologies are being implemented in a context where ethnic inequalities, inadequate oversight and poor data collection already persist.

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

Home Office Response

A Home Office spokesperson stated: “The Home Office takes the findings of the report seriously and we have implemented changes. A new algorithm has been independently tested and acquired, which has demonstrated no measurable discrimination. It will be trialled early next year and will be subject to evaluation.

“The foremost aim is ensuring public safety. This gamechanging technology will support officers to apprehend and prosecute offenders. There is human involvement in each stage of the process and no arrest or charge would be pursued without trained officers meticulously examining the results.”