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Police forces across the United Kingdom successfully lobbied to use a face scanning system acknowledged as discriminatory against women, young people, and members of ethnic minority groups, after complaining that a more accurate version generated a reduced number of investigative leads.

The Technology in Practice

British police utilize the police national database (PND) to carry out retrospective facial recognition searches. This process entails matching a reference photograph of a suspect against a repository of more than 19 million custody photos to find possible hits.

Admitted Bias

The UK interior ministry admitted last week that the technology was biased. This acknowledgment came after a study by the government's National Physical Laboratory found it misidentified people of Black and Asian heritage and women at much greater frequency than Caucasian males. The Home Office stated it “had acted on the findings”.

“This raises the question of whether this technology only becomes useful if users tolerate discrimination in race and sex. Operational ease is a poor argument for disregarding basic freedoms.”

Known Issue

Official papers show that this discriminatory flaw has been known about for over twelve months. Furthermore, police forces lobbied to reverse an initial decision 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 suggest false positives for photos of women, Black people, and those aged 40 and under.

A Policy U-Turn

In response, the National Police Chiefs’ Council (NPCC) mandated that the confidence threshold required for potential matches be raised to a level where the bias was significantly reduced.

However, this decision was reversed the next month following complaints from police that the adjusted system was generating fewer “useful lines of inquiry”. NPCC documents show the stricter setting cut the number of searches that yielded possible identifications from over half to a just 14%.

Profound Inequalities

Although the Home Office and NPCC declined to specify what setting is currently used, the recent independent review discovered the system could generate incorrect matches for women of Black heritage almost 100 times more often than for Caucasian women at certain settings.

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

Operational Effectiveness vs. Bias

Describing the impact of the temporary raise to the system's confidence threshold, the NPCC documents note: “The change greatly lessens the effect of bias across legally safeguarded attributes of race, generation and gender but had a significant negative impact on police efficiency”. The papers further note that police units complained that “a once effective tactic returned outcomes of limited benefit”.

Wider Implementation Proposals

Meanwhile, the UK administration has opened a two-and-a-half-month public review on its proposals to widen the use of biometric scanning systems. The minister for police the relevant minister has described the technology as the “biggest breakthrough since genetic fingerprinting”.

Expert and Oversight Concerns

The chair of a police oversight board, chair of the advisory panel for the police race action plan, commented: “We observed very little discussion in equality strategy sessions of the facial recognition rollout despite obvious cross-over with the strategy's goals.

“These revelations show yet again that the pledges to combat discrimination policing has made through the race action plan are not being translated into wider practice. Our reports have warned that innovative tools are being implemented in a landscape where ethnic inequalities, weak scrutiny and faulty information gathering continue to exist.

“Any use of facial recognition must adhere to strict national standards, be independently scrutinised, and demonstrate it reduces rather than exacerbates ethnic bias.”

Official Statement

A government representative said: “The Home Office takes the findings of the study with utmost gravity and we have implemented changes. A updated software has been externally evaluated and acquired, which has no statistically significant bias. It will be tested early next year and will be undergo evaluation.

“Our priority is ensuring public safety. This revolutionary tool will support officers to put criminals and rapists behind bars. There is officer review in each stage of the process and no further action would be pursued without trained officers carefully reviewing the results.”