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Law enforcement agencies across the UK successfully lobbied to use a face scanning system known to be biased against females, young people, and members of ethnic minority groups, after complaining that a more accurate version generated fewer potential suspects.

How the System Works

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

Admitted Bias

The Home Office admitted last week that the system was biased. This acknowledgment came after a study by the National Physical Laboratory (NPL) found it incorrectly matched Black and Asian people and females at significantly higher rates than white men. The ministry stated it “had acted on the findings”.

“This raises the issue of whether this technology only becomes effective if users tolerate biases in race and gender. Convenience is a poor argument for disregarding fundamental rights.”

Long-Standing Problem

Official papers show that this bias has been known about for over twelve months. Furthermore, police forces lobbied to reverse an earlier ruling that was intended to address the problem.

Senior officers were notified of the system's bias in late 2024. The government-ordered laboratory study concluded the system was more likely to produce incorrect matches for images depicting females, Black people, and those aged 40 and under.

A Reversed Decision

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

However, this decision was overturned the next month following complaints from police that the adjusted system was generating a lower number of “investigative leads”. NPCC documents show the stricter setting reduced the number of queries resulting in possible identifications from over half to a mere 14%.

Severe Disparities

Although the Home Office and NPCC declined to specify what setting is currently used, the latest independent review discovered the system could produce false positives for Black women nearly a hundred times more often than for Caucasian women at specific configurations.

The ministry commented on these results: “The testing found that in a limited set of circumstances the algorithm is has a greater tendency to wrongly flag some population segments in its match reports.”

Balancing Utility and Fairness

Describing the impact of the brief increase to the system's accuracy setting, the police records note: “This adjustment significantly reduces the impact of bias across protected characteristics of ethnicity, age and sex but had a significant negative impact on operational effectiveness”. The papers further note that police units argued that “a previously useful tool returned results of limited benefit”.

Wider Implementation Proposals

Meanwhile, the government has opened a ten-week consultation on its proposals to expand 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, head of the advisory panel for the police race action plan, said: “We observed very little discussion through race action plan meetings of the facial recognition rollout despite obvious cross-over with the plan’s concerns.

“This disclosure show once again that the pledges to combat discrimination the police has made via the race action plan are failing to be integrated into broader operations. Our reports have warned that new technologies are being implemented in a landscape where racial disparities, weak scrutiny and faulty information gathering continue to exist.

“Any use of facial recognition must adhere to strict national standards, be independently scrutinised, and prove it diminishes rather than compounds racial disparity.”

Home Office Response

A government representative said: “We treat the findings of the report seriously and we have implemented changes. A new algorithm has been independently tested and procured, which has demonstrated no measurable discrimination. It will be tested early next year and will be undergo further assessment.

“Our priority is protecting the public. This revolutionary tool will assist police to apprehend and prosecute offenders. There is officer review in every step of the process and no arrest or charge would be taken without specialist personnel carefully reviewing the output.”