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Police forces across the UK effectively campaigned to deploy a face scanning system known to be biased against women, young people, and individuals from ethnic minority groups, following complaints that a more accurate version produced a reduced number of investigative leads.

How the System Works

British police utilize the national police database to carry out retrospective facial recognition searches. This process involves matching a reference photograph of a suspect against a repository of over 19 million custody photos to find possible hits.

Acknowledged Discrimination

The Home Office conceded last week that the technology was biased. This admission followed a study by the government's National Physical Laboratory determined it misidentified Black and Asian people and females at significantly higher rates than white men. The Home Office stated it “had acted on the findings”.

“This raises the question of whether this technology only becomes effective if users accept discrimination in race and gender. Convenience is a poor argument for disregarding basic freedoms.”

Known Issue

Official papers reveal that this bias has been recognized for over twelve months. Furthermore, law enforcement lobbied to reverse an initial decision that was designed to address the problem.

Senior officers were notified of the system's bias in late 2024. The Home Office-commissioned laboratory study found the system was more likely to produce incorrect matches for photos of women, individuals of Black ethnicity, and those aged 40 and under.

A Reversed Decision

In reaction, the national police leadership body ordered 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 next month after forces complained that the adjusted system was generating fewer “investigative leads”. NPCC documents indicate the stricter setting reduced the number of queries that yielded possible identifications from 56% 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 found the system could produce false positives for women of Black heritage almost 100 times more frequently than for Caucasian women at certain settings.

The Home Office stated on these findings: “Our evaluation found that in a specific scenarios the algorithm is has a greater tendency to wrongly flag some population segments in its match reports.”

Operational Effectiveness vs. Bias

Describing the effect of the brief increase to the system's confidence threshold, the NPCC documents note: “The change significantly reduces the impact of bias across protected characteristics of race, generation and sex but had a significant negative impact on operational effectiveness”. The papers add that forces argued that “a once effective tactic now delivered outcomes of limited benefit”.

Broader Rollout Plans

Meanwhile, the government has opened a ten-week public review on its plans to widen the use of biometric scanning systems. Policing minister Sarah Jones has labeled the tool as the “most significant advance since genetic fingerprinting”.

Expert and Oversight Concerns

Abimbola Johnson, head of the advisory panel for the police race action plan, commented: “We observed scant consideration through race action plan meetings of the technology deployment even with clear relevance with the plan’s concerns.

“These revelations demonstrate yet again that the pledges to combat discrimination policing has made through the race action plan are failing to be integrated into broader operations. Independent assessments have cautioned that new technologies are being implemented in a context where racial disparities, weak scrutiny and faulty information gathering already persist.

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

Official Statement

A Home Office spokesperson said: “We treat the findings of the study seriously and we have already taken action. 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 further assessment.

“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 each stage of the process and no arrest or charge would be pursued without specialist personnel carefully reviewing the results.”