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Police forces across the UK effectively campaigned to deploy a face scanning system acknowledged as biased against females, young people, and members of minority ethnic backgrounds, after complaining that a less biased version generated fewer investigative leads.

The Technology in Practice

UK forces utilize the police national database (PND) to conduct retrospective facial recognition searches. This process involves comparing a “probe image” of a suspect against a repository of over 19 million mugshots to find possible hits.

Admitted Bias

The UK interior ministry conceded last week that the technology was flawed. This acknowledgment followed a review by the National Physical Laboratory (NPL) found it misidentified Black and Asian people and females at much greater frequency than Caucasian males. The ministry stated it “had acted on the findings”.

“It prompts the question of whether this technology only becomes useful if users tolerate discrimination in race and gender. Convenience is a poor argument for disregarding fundamental rights.”

Known Issue

Official papers reveal that this discriminatory flaw has been known about for over twelve months. Furthermore, police forces lobbied to reverse an earlier ruling that was intended to address the problem.

Police bosses were informed of the system's bias in late 2024. The government-ordered laboratory study found the system was more likely to produce incorrect matches for photos of females, Black people, and those aged 40 and under.

A Reversed Decision

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

However, this decision was overturned the next month following complaints from police that the adjusted system was producing fewer “investigative leads”. Internal records indicate the stricter setting cut the number of searches that yielded possible identifications from 56% to a just under 15%.

Profound Inequalities

Although the authorities refused to say what threshold is now in operation, the recent independent review found the system could generate incorrect matches for Black women nearly a hundred times more frequently than for white women at certain settings.

The ministry stated on these findings: “Our evaluation found that in a specific scenarios the software is has a greater tendency to wrongly flag some population segments in its search results.”

Operational Effectiveness vs. Bias

Describing the effect of the brief increase to the system's confidence threshold, the police records note: “This adjustment significantly reduces the impact of discrimination across legally safeguarded attributes of race, generation and gender but had a significant negative impact on police efficiency”. The papers add that police units complained that “a once effective tactic returned outcomes of questionable value”.

Wider Implementation Proposals

Meanwhile, the government has launched a two-and-a-half-month public review on its proposals to expand the use of biometric scanning systems. The minister for police Sarah Jones has described the technology as the “most significant advance since genetic fingerprinting”.

Expert and Oversight Concerns

The chair of a police oversight board, head of the independent scrutiny and oversight board for the police race action plan, commented: “We observed very little discussion through race action plan meetings of the technology deployment even with obvious cross-over with the strategy's goals.

“These revelations demonstrate yet again that the pledges to combat discrimination the police has undertaken through the race action plan are failing to be integrated into wider practice. Our reports have cautioned that new technologies are being rolled out in a context where ethnic inequalities, inadequate oversight and poor data collection already persist.

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

Official Statement

A Home Office spokesperson stated: “We takes the findings of the report with utmost gravity and we have implemented changes. A updated software has been externally evaluated and acquired, which has demonstrated no measurable discrimination. It will be tested in the coming months and will be subject to further assessment.

“The foremost aim is ensuring public safety. This gamechanging technology will assist officers to put criminals and rapists behind bars. There is officer review in each stage of the procedure and no arrest or charge would be pursued without trained officers meticulously examining the output.”