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Police forces across the United Kingdom effectively campaigned to deploy a facial recognition system known to be biased against women, youths, and individuals from minority ethnic backgrounds, after complaining that a less biased 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 “probe image” of a person of interest against a repository of more than 19 million mugshots to find potential matches.

Admitted Bias

The UK interior ministry conceded last week that the system was biased. This admission came after a study by the government's National Physical Laboratory found it misidentified people of Black and Asian heritage and women at significantly higher rates than white men. The ministry stated it “had acted on the findings”.

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

Long-Standing Problem

Internal documents show that this discriminatory flaw has been known about for more than a year. Furthermore, police forces argued to overturn an initial decision that was designed 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 suggest false positives for photos of females, individuals of Black ethnicity, and those under 40 years old.

A Policy U-Turn

In response, the national police leadership body mandated that the confidence threshold required for potential matches be raised to a level where the disparity was significantly reduced.

However, this decision was overturned the following month after forces complained that the modified technology was generating a lower number of “investigative leads”. Internal records indicate the higher threshold cut the proportion of queries resulting in potential matches from over half to a just under 15%.

Profound Inequalities

Although the Home Office and NPCC declined to specify what setting is currently used, the recent NPL study found the system could produce incorrect matches for Black women almost 100 times more often than for white women at certain settings.

The ministry commented on these findings: “Our evaluation found that in a specific scenarios 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 brief increase to the system's confidence threshold, the police records state: “This adjustment significantly reduces the impact of bias across protected characteristics of race, age and sex but had a substantially detrimental effect on police efficiency”. The papers further note that police units argued that “a previously useful tool returned results of limited benefit”.

Broader Rollout Plans

Meanwhile, the UK administration has launched a two-and-a-half-month public review on its proposals to expand the use of biometric scanning systems. Policing minister the relevant minister has labeled the tool as the “biggest breakthrough since DNA matching”.

Criticism from Advisors and Monitors

Abimbola Johnson, chair of the advisory panel for the national policing equality strategy, commented: “There was very little discussion through race action plan meetings of the technology deployment despite clear relevance with the strategy's goals.

“These revelations demonstrate yet again that the pledges to combat discrimination the police has undertaken through the race action plan are failing to be integrated into wider practice. Independent assessments have warned that innovative tools are being implemented in a landscape where racial disparities, inadequate oversight and faulty information gathering continue to exist.

“All deployment of this technology must adhere to rigorous official guidelines, be subject to external review, and prove it reduces rather than exacerbates racial disparity.”

Home Office Response

A government representative said: “We treat the findings of the study seriously and we have already taken action. A new algorithm has been externally evaluated and acquired, which has no statistically significant bias. It will be trialled early next year and will be subject to evaluation.

“The foremost aim is protecting the public. 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 taken without specialist personnel carefully reviewing the results.”