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Law enforcement agencies across the UK successfully lobbied to use a facial recognition system known to be biased against females, youths, and individuals from minority ethnic backgrounds, following complaints that a less biased version produced fewer investigative leads.

How the System Works

British police use the police national database (PND) to conduct retrospective facial recognition searches. This process entails comparing a reference photograph of a person of interest against a repository of over 19 million mugshots to find possible hits.

Acknowledged Discrimination

The UK interior ministry conceded last week that the system was flawed. This acknowledgment came after a review by the government's National Physical Laboratory found it incorrectly matched people of Black and Asian heritage and women at significantly higher rates than white men. The Home Office said it “had acted on the findings”.

“This raises the issue of whether this technology only becomes useful if users tolerate biases in race and sex. Operational ease is a weak argument for overriding basic freedoms.”

Long-Standing Problem

Internal documents reveal that this bias has been known about for over twelve months. Furthermore, police forces lobbied to reverse an initial decision that was designed to mitigate the problem.

Police bosses were informed of the algorithmic discrimination in late 2024. The Home Office-commissioned laboratory study found the system was had a higher probability to produce incorrect matches for photos of women, Black people, and those under 40 years old.

A Reversed Decision

In response, the National Police Chiefs’ Council (NPCC) mandated that the confidence threshold required for possible hits be increased to a level where the bias was greatly diminished.

However, this decision was overturned the following month after forces complained that the modified technology was producing fewer “useful lines of inquiry”. NPCC documents indicate the stricter setting reduced the number of searches that yielded possible identifications from over half to a mere 14%.

Profound Inequalities

Although the authorities refused to say what threshold is now in operation, the recent independent review found the system could generate false positives for Black women almost 100 times more frequently than for Caucasian women at certain settings.

The Home Office commented on these findings: “The testing found that in a specific scenarios the algorithm is has a greater tendency to incorrectly include some population segments in its search results.”

Balancing Utility and Fairness

Describing the effect of the temporary raise to the system's accuracy setting, the NPCC documents note: “This adjustment significantly reduces the effect of discrimination across protected characteristics of race, generation and gender but had a significant negative impact on police efficiency”. The documents add that forces complained that “a once effective tactic now delivered results of questionable value”.

Wider Implementation Proposals

Meanwhile, the UK administration has opened a two-and-a-half-month consultation on its proposals to expand the use of biometric scanning systems. Policing minister Sarah Jones has labeled the technology as the “biggest breakthrough since genetic fingerprinting”.

Expert and Oversight Concerns

Abimbola Johnson, chair of the independent scrutiny and oversight board for the national policing equality strategy, said: “There was very little discussion in equality strategy sessions of the facial recognition rollout despite obvious cross-over with the plan’s concerns.

“These revelations show yet again that the anti-racism commitments policing has undertaken via the equality initiative are failing to be integrated into broader operations. Independent assessments have warned that innovative tools are being rolled out in a context 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 diminishes rather than exacerbates ethnic bias.”

Official Statement

A government representative said: “The Home Office treat the conclusions of the study with utmost gravity and we have already taken action. A new algorithm has been externally evaluated and acquired, which has demonstrated no measurable discrimination. It will be trialled early next year and will be undergo further assessment.

“Our priority is protecting the public. This revolutionary tool will support police to apprehend and prosecute offenders. There is officer review in each stage of the procedure and no arrest or charge would be taken without trained officers meticulously examining the output.”