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Law enforcement agencies across the United Kingdom successfully lobbied to use a face scanning system known to be discriminatory against females, youths, and members of minority ethnic backgrounds, following complaints that a less biased version produced a reduced number of potential suspects.

The Technology in Practice

British police utilize the national police database to conduct retrospective facial recognition searches. This process involves comparing a “probe image” of a person of interest against a repository of more than 19 million mugshots to identify potential matches.

Admitted Bias

The Home Office admitted last week that the system was biased. This admission came after a study 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 ministry said it “had acted on the findings”.

“This raises the question of whether facial recognition only becomes effective if users accept discrimination in ethnicity and gender. Convenience is a poor argument for overriding basic freedoms.”

Long-Standing Problem

Official papers reveal that this discriminatory flaw has been recognized for over twelve months. Furthermore, law enforcement lobbied to reverse an earlier ruling that was designed to mitigate the problem.

Police bosses were notified of the algorithmic discrimination in late 2024. The Home Office-commissioned NPL review found the system was more likely to produce false positives for photos of females, individuals of Black ethnicity, and those under 40 years old.

A Reversed Decision

In response, the National Police Chiefs’ Council (NPCC) mandated that the confidence threshold required for potential matches 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 “investigative leads”. NPCC documents indicate the stricter setting reduced the number of searches resulting in potential matches from over half to a just under 15%.

Profound Inequalities

Although the Home Office and NPCC refused to say what threshold is currently used, the recent NPL study discovered the system could generate incorrect matches for Black women nearly a hundred times more frequently than for Caucasian women at certain settings.

The Home Office commented on these findings: “The testing identified that in a limited set of circumstances the algorithm is has a greater tendency to wrongly flag some demographic groups in its search results.”

Operational Effectiveness vs. Bias

Outlining the impact of the temporary raise to the system's confidence threshold, the police records state: “This adjustment greatly lessens the effect of discrimination across legally safeguarded attributes of race, generation and sex but had a substantially detrimental effect on operational effectiveness”. The papers add that police units argued that “a once effective tactic now delivered outcomes of questionable value”.

Broader Rollout Plans

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

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 scant discussion through race action plan meetings of the technology deployment even with obvious cross-over with the plan’s concerns.

“This disclosure show yet again that the pledges to combat discrimination the police 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 ethnic inequalities, weak scrutiny and poor data collection already persist.

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

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 no statistically significant bias. It will be trialled early next year and will be subject to further assessment.

“The foremost aim is protecting the public. This revolutionary tool will support police to put criminals and rapists behind bars. There is human involvement in each stage of the process and no further action would be pursued without specialist personnel meticulously examining the results.”