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Police forces across the UK successfully lobbied to deploy a facial recognition system known to be discriminatory against women, youths, and individuals from minority ethnic backgrounds, after complaining that a more accurate version produced fewer investigative leads.

The Technology in Practice

UK forces use the police national database (PND) to carry out searches using historical face recognition. This process entails comparing a “probe image” of a suspect against a repository of over 19 million mugshots to identify potential matches.

Acknowledged Discrimination

The Home Office admitted last week that the technology was flawed. This admission followed a study by the National Physical Laboratory (NPL) found it incorrectly matched Black and Asian people and females at significantly higher rates than Caucasian males. The ministry stated it “took steps on the findings”.

“It prompts the question of whether facial recognition only becomes effective if users tolerate biases in ethnicity and sex. Operational ease is a poor argument for disregarding basic freedoms.”

Known Issue

Official papers reveal that this bias has been known about for more than a year. Furthermore, police forces 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 had a higher probability to suggest incorrect matches for photos of females, Black people, and those under 40 years old.

A Reversed Decision

In response, the National Police Chiefs’ Council (NPCC) mandated that the accuracy setting required for potential matches be raised to a point where the disparity was significantly reduced.

However, this directive was reversed the next month following complaints from police that the adjusted system was producing fewer “useful lines of inquiry”. Internal records indicate the stricter setting reduced the proportion of queries that yielded possible identifications from over half to a mere 14%.

Severe Disparities

Although the Home Office and NPCC declined to specify what threshold is now in operation, the recent independent review found the system could produce false positives for women of Black heritage nearly a hundred times more frequently than for Caucasian women at certain settings.

The ministry stated on these findings: “Our evaluation found that in a specific scenarios the software is has a greater tendency to incorrectly include some population segments in its search results.”

Balancing Utility and Fairness

Describing the impact of the brief increase to the system's accuracy setting, the NPCC documents note: “The change significantly reduces the effect of discrimination across protected characteristics of ethnicity, age and gender but had a significant negative impact on police efficiency”. The documents add that police units complained that “a once effective tactic returned outcomes of limited benefit”.

Broader Rollout Plans

Meanwhile, the government has opened a ten-week consultation on its plans to expand the use of biometric scanning systems. Policing minister Sarah Jones has described the tool as the “biggest breakthrough since DNA matching”.

Expert and Oversight Concerns

Abimbola Johnson, head of the advisory panel for the national policing equality strategy, commented: “We observed scant discussion through equality strategy sessions of the facial recognition rollout even with clear relevance with the plan’s concerns.

“This disclosure show yet again that the anti-racism commitments the police has made through the equality initiative are failing to be integrated into broader operations. Our reports have warned that innovative tools are being implemented in a context where racial disparities, weak scrutiny and poor data collection continue to exist.

“Any use of this technology must meet rigorous official guidelines, be independently scrutinised, and demonstrate it reduces rather than compounds ethnic bias.”

Home Office Response

A Home Office spokesperson said: “We takes the conclusions of the study seriously and we have already taken action. A new algorithm has been independently tested and procured, which has no statistically significant bias. It will be trialled early next year and will be subject to evaluation.

“Our priority is ensuring public safety. This gamechanging technology will support officers to put criminals and rapists behind bars. There is officer review in each stage of the procedure and no arrest or charge would be taken without specialist personnel carefully reviewing the results.”