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Law enforcement agencies across the UK successfully lobbied to use a face scanning system acknowledged as biased against females, youths, and members of minority ethnic backgrounds, following complaints that a less biased version generated a reduced number of potential suspects.

How the System Works

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

Acknowledged Discrimination

The Home Office admitted last week that the system was biased. This acknowledgment followed a study by the government's National Physical Laboratory found it misidentified Black and Asian people and women at much greater frequency than white men. The Home Office said it “took steps on the findings”.

“This raises the issue of whether this technology only becomes effective if users accept biases in ethnicity and sex. Operational ease is a weak argument for overriding fundamental rights.”

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 earlier ruling that was intended to mitigate the problem.

Senior officers were notified of the system's bias in September 2024. The government-ordered laboratory study found the system was had a higher probability to produce false positives for photos of women, individuals of Black ethnicity, and those aged 40 and under.

A Reversed Decision

In response, the National Police Chiefs’ Council (NPCC) mandated that the accuracy setting required for potential matches be increased to a level where the disparity was greatly diminished.

However, this directive was overturned the next month following complaints from police that the adjusted system was generating a lower number of “investigative leads”. Internal records show the stricter setting reduced the proportion of searches resulting in possible identifications from over half to a just under 15%.

Profound Inequalities

Although the Home Office and NPCC refused to say what setting is currently used, the recent independent review found the system could produce false positives for Black women nearly a hundred times more frequently than for white women at certain settings.

The ministry stated on these results: “Our evaluation found that in a limited set of circumstances the software is more likely to incorrectly include some demographic groups 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: “The change greatly lessens the impact of bias across protected characteristics of race, age and gender but had a substantially detrimental effect on police efficiency”. The papers add that forces complained that “a once effective tactic returned results of limited benefit”.

Broader Rollout Plans

Meanwhile, the UK administration has opened a two-and-a-half-month consultation on its plans to widen 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

The chair of a police oversight board, head of the advisory panel for the police race action plan, said: “We observed scant discussion in race action plan meetings of the facial recognition rollout despite obvious cross-over with the plan’s concerns.

“These revelations demonstrate yet again that the anti-racism commitments the police has undertaken through the equality initiative are failing to be integrated into broader operations. Our reports have warned that innovative tools are being implemented in a landscape where ethnic inequalities, weak scrutiny and poor data collection already persist.

“Any use of this technology must adhere to strict national standards, be subject to external review, and demonstrate it reduces rather than compounds ethnic bias.”

Official Statement

A government representative said: “The Home Office treat the conclusions of the report seriously and we have implemented changes. A new algorithm has been externally evaluated and acquired, which has demonstrated no measurable discrimination. It will be tested early next year and will be subject to further assessment.

“Our priority is protecting the public. This gamechanging technology will support police 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 meticulously examining the results.”