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Police forces across the United Kingdom effectively campaigned to deploy a face scanning system known to be biased against females, youths, and members of ethnic minority groups, following complaints that a more accurate version generated fewer potential suspects.

The Technology in Practice

UK forces 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 database of more than 19 million custody photos to identify potential matches.

Acknowledged Discrimination

The UK interior ministry admitted last week that the technology was biased. This admission followed 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 “took steps on the findings”.

“It prompts the question of whether this technology only becomes effective if users accept discrimination in ethnicity and sex. Operational ease is a poor argument for disregarding fundamental rights.”

Known Issue

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

Senior officers were notified of the system's bias in late 2024. The Home Office-commissioned laboratory study concluded the system was had a higher probability to suggest false positives for images depicting females, individuals of Black ethnicity, and those aged 40 and under.

A Policy U-Turn

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

However, this directive was reversed the next month after forces complained that the modified technology was generating fewer “investigative leads”. Internal records indicate the higher threshold cut the number of queries that yielded potential matches from 56% to a mere 14%.

Profound Inequalities

Although the authorities declined to specify what setting is now in operation, the latest independent review found the system could produce incorrect matches for Black women nearly a hundred times more frequently than for white women at specific configurations.

The Home Office commented on these results: “Our evaluation found that in a limited set of circumstances the algorithm is has a greater tendency to wrongly flag some demographic groups in its match reports.”

Operational Effectiveness vs. Bias

Outlining the impact of the temporary raise to the system's confidence threshold, the NPCC documents state: “The change significantly reduces the effect of discrimination across legally safeguarded attributes of ethnicity, generation and gender but had a substantially detrimental effect on police efficiency”. The papers add that forces argued that “a previously useful tool returned results of questionable value”.

Wider Implementation Proposals

Meanwhile, the government has launched a ten-week consultation on its proposals to expand the use of facial recognition technology. Policing minister Sarah Jones has described the tool as the “biggest breakthrough since genetic fingerprinting”.

Expert and Oversight Concerns

The chair of a police oversight board, head of the advisory panel for the national policing equality strategy, said: “There was very little consideration through race action plan meetings of the technology deployment despite clear relevance with the strategy's goals.

“This disclosure show yet again that the pledges to combat discrimination 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 context where ethnic inequalities, inadequate oversight and poor data collection continue to exist.

“All deployment of this technology must adhere to strict national standards, be independently scrutinised, and demonstrate it diminishes rather than exacerbates ethnic bias.”

Official Statement

A Home Office spokesperson said: “We treat the findings of the study with utmost gravity and we have implemented changes. A updated software has been externally evaluated and procured, which has demonstrated no measurable discrimination. It will be tested early next year and will be subject to further assessment.

“The foremost aim is protecting the public. This revolutionary tool will assist police to put criminals and rapists behind bars. There is officer review in every step of the procedure and no further action would be pursued without specialist personnel carefully reviewing the output.”