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Police forces across the UK effectively campaigned to use a face scanning system known to be discriminatory against women, young people, 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 procedure involves comparing a reference photograph of a suspect against a database of more than 19 million mugshots to find possible hits.

Admitted Bias

The Home Office conceded last week that the system was biased. This acknowledgment came after a review by the government's National Physical Laboratory determined it incorrectly matched Black and Asian people and women at significantly higher rates than Caucasian males. The Home Office stated it “had acted on the findings”.

“It prompts the question of whether this technology only becomes useful if users accept biases in race and sex. Convenience is a poor argument for overriding fundamental rights.”

Known Issue

Internal documents show that this discriminatory flaw has been known about for more than a year. Furthermore, police forces lobbied to reverse an initial decision that was intended to mitigate the problem.

Senior officers were notified of the algorithmic discrimination in September 2024. The Home Office-commissioned NPL review concluded the system was had a higher probability to suggest false positives 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 greatly diminished.

However, this decision was overturned the next month after forces complained that the modified technology was producing fewer “investigative leads”. NPCC documents show the higher threshold cut the number of searches that yielded possible identifications from 56% to a mere 14%.

Severe Disparities

Although the Home Office and NPCC refused to say what setting is now in operation, the recent NPL study discovered the system could generate incorrect matches for Black women nearly a hundred times more often than for white women at certain settings.

The ministry stated on these results: “The testing identified that in a specific scenarios the algorithm is has a greater tendency to wrongly flag some population segments in its match reports.”

Balancing Utility and Fairness

Outlining the effect of the brief increase to the system's accuracy setting, the police records note: “The change greatly lessens the impact of discrimination across protected characteristics of race, generation and gender but had a substantially detrimental effect on police efficiency”. The documents add that forces complained that “a once effective tactic now delivered results of limited benefit”.

Broader Rollout Plans

Meanwhile, the UK administration has opened a ten-week public review on its proposals to expand the use of biometric scanning systems. Policing minister the relevant minister has described the technology as the “biggest breakthrough since DNA matching”.

Expert and Oversight Concerns

Abimbola Johnson, chair of the advisory panel for the police race action plan, commented: “We observed very little consideration through race action plan meetings of the facial recognition rollout even with obvious cross-over with the plan’s concerns.

“These revelations show once again that the pledges to combat discrimination policing has made through the equality initiative are not being translated into broader operations. Our reports have cautioned that new technologies are being implemented in a context where ethnic inequalities, weak scrutiny and faulty information gathering already persist.

“All deployment of this technology must meet rigorous official guidelines, be subject to external review, and prove it diminishes rather than exacerbates racial disparity.”

Home Office Response

A Home Office spokesperson stated: “We treat the findings of the study with utmost gravity and we have implemented changes. A new algorithm has been independently tested and acquired, which has no statistically significant bias. It will be trialled early next year and will be undergo evaluation.

“The foremost aim is ensuring public safety. This gamechanging technology will assist police to put criminals and rapists behind bars. There is human involvement in every step of the process and no further action would be pursued without trained officers carefully reviewing the results.”