🔗 Share this article

Law enforcement agencies across the UK successfully lobbied to deploy a face scanning system known to be biased against females, young people, and individuals from ethnic minority groups, after complaining that a more accurate version produced fewer investigative leads.

The Technology in Practice

UK forces use the police national database (PND) to conduct searches using historical face recognition. This process entails matching a “probe image” of a suspect against a database of more than 19 million mugshots to find potential matches.

Acknowledged Discrimination

The Home Office admitted last week that the technology was flawed. This acknowledgment followed a review by the National Physical Laboratory (NPL) found it misidentified Black and Asian people and women at significantly higher rates than white men. The Home Office stated 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 basic freedoms.”

Known Issue

Official papers show that this bias has been known about for over twelve months. Furthermore, law enforcement argued to overturn an initial decision that was intended to address the problem.

Senior officers were notified of the system's bias in September 2024. The Home Office-commissioned laboratory study found the system was more likely to suggest false positives for images depicting women, Black people, and those aged 40 and under.

A Reversed Decision

In response, the National Police Chiefs’ Council (NPCC) ordered that the confidence threshold required for potential matches be raised to a point where the disparity was greatly diminished.

However, this directive was overturned the following month after forces complained that the modified technology was producing a lower number of “useful lines of inquiry”. Internal records indicate the stricter setting cut the proportion of searches resulting in potential matches from over half to a mere under 15%.

Profound Inequalities

Although the Home Office and NPCC declined to specify what setting is currently used, the latest NPL study found the system could produce incorrect matches for Black women nearly a hundred times more often than for Caucasian women at specific configurations.

The ministry stated on these results: “Our evaluation found that in a limited set of circumstances the software is more likely to wrongly flag some demographic groups 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: “This adjustment greatly lessens the impact of discrimination across protected characteristics of ethnicity, age and sex but had a substantially detrimental effect on police efficiency”. The papers further note that forces argued that “a once effective tactic returned results of limited benefit”.

Broader Rollout Plans

Meanwhile, the government has opened a ten-week public review on its plans to widen the use of facial recognition technology. Policing minister Sarah Jones has labeled the tool as the “biggest breakthrough since genetic fingerprinting”.

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 obvious cross-over with the strategy's goals.

“This disclosure demonstrate once again that the anti-racism commitments policing has undertaken through the equality initiative are not being translated into wider practice. Our reports have warned that new technologies are being implemented in a landscape where racial disparities, weak scrutiny and poor data collection already persist.

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

Home Office Response

A government representative stated: “We treat the findings of the study seriously and we have already taken action. A updated software has been externally evaluated and procured, which has no statistically significant bias. It will be trialled early next year and will be undergo evaluation.

“Our priority is protecting the public. This gamechanging technology will assist officers to apprehend and prosecute offenders. There is officer review in every step of the procedure and no further action would be taken without trained officers carefully reviewing the results.”