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Law enforcement agencies across the United Kingdom effectively campaigned to use a face scanning system acknowledged as biased against women, young people, and individuals from minority ethnic backgrounds, following complaints that a more accurate version produced fewer potential suspects.

How the System Works

UK forces utilize the police national database (PND) to conduct retrospective facial recognition searches. This process entails comparing a “probe image” of a person of interest against a repository of over 19 million custody photos to identify possible hits.

Acknowledged Discrimination

The Home Office conceded last week that the technology was biased. This admission followed a review by the government's National Physical Laboratory found it incorrectly matched Black and Asian people and women at much greater frequency than white men. The Home Office said it “had acted on the findings”.

“This raises the issue of whether facial recognition only becomes effective if users accept discrimination in ethnicity and gender. Operational ease is a weak argument for disregarding basic freedoms.”

Known Issue

Official papers reveal that this bias has been known about for more than a year. Furthermore, law enforcement argued to overturn an earlier ruling that was designed to address the problem.

Senior officers were notified of the system's bias in late 2024. The Home Office-commissioned NPL review concluded the system was more likely to produce incorrect matches for images depicting women, Black people, and those under 40 years old.

A Policy U-Turn

In reaction, the national police leadership body mandated that the accuracy setting required for possible hits be raised to a point where the bias was significantly reduced.

However, this decision was reversed the next month following complaints from police that the adjusted system was producing a lower number of “useful lines of inquiry”. NPCC documents indicate the stricter setting cut the proportion of searches that yielded possible identifications from 56% to a just under 15%.

Profound Inequalities

Although the authorities refused to say what setting is currently used, the recent NPL study found the system could produce false positives for Black women 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 limited set of circumstances the algorithm is more likely to incorrectly include some demographic groups in its search results.”

Balancing Utility and Fairness

Describing the effect of the brief increase to the system's confidence threshold, the police records note: “The change greatly lessens the impact of bias across legally safeguarded attributes of ethnicity, generation and sex but had a substantially detrimental effect on police efficiency”. The papers further note that forces argued that “a previously useful tool now delivered results of questionable value”.

Broader Rollout Plans

Meanwhile, the UK administration has launched a ten-week consultation on its proposals to widen the use of facial recognition technology. The minister for police the relevant minister has described the tool as the “most significant advance since DNA matching”.

Criticism from Advisors and Monitors

The chair of a police oversight board, head of the advisory panel for the police race action plan, said: “There was very little consideration through equality strategy sessions of the technology deployment despite obvious cross-over with the strategy's goals.

“These revelations show once again that the anti-racism commitments policing has undertaken via the equality initiative are not being translated into wider practice. Independent assessments have warned that innovative tools are being implemented in a landscape where ethnic inequalities, weak scrutiny and poor data collection already persist.

“All deployment of this technology must adhere to rigorous official guidelines, be independently scrutinised, and prove it diminishes rather than compounds ethnic bias.”

Home Office Response

A government representative stated: “We treat the conclusions of the report with utmost gravity 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 subject to evaluation.

“Our priority is protecting the public. This gamechanging technology will support officers to put criminals and rapists behind bars. There is officer review in every step of the procedure and no arrest or charge would be taken without trained officers carefully reviewing the results.”