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Law enforcement agencies across the United Kingdom successfully lobbied to deploy a face scanning system acknowledged as biased against females, youths, and individuals from ethnic minority groups, after complaining that a more accurate version generated fewer investigative leads.

How the System Works

British police use the national police database to conduct searches using historical face recognition. This process entails matching a reference photograph of a suspect against a repository of more than 19 million mugshots to identify possible hits.

Admitted Bias

The UK interior ministry admitted last week that the system was biased. This admission followed a review by the National Physical Laboratory (NPL) determined it incorrectly matched people of Black and Asian heritage and women at significantly higher rates than white men. The Home Office said it “had acted on the findings”.

“It prompts the question of whether facial recognition only becomes effective if users accept biases in ethnicity and sex. Operational ease is a poor argument for disregarding fundamental rights.”

Known Issue

Internal documents reveal that this discriminatory flaw has been known about for more than a year. Furthermore, police forces argued to overturn an initial decision that was designed to address the problem.

Police bosses were informed of the system's bias in late 2024. The government-ordered NPL review found the system was more likely to suggest false positives for images depicting women, Black people, and those aged 40 and under.

A Reversed Decision

In response, the national police leadership body mandated that the confidence threshold required for possible hits be increased to a point where the bias was greatly diminished.

However, this decision was reversed the next month following complaints from police that the modified technology was generating fewer “investigative leads”. NPCC documents show the higher threshold reduced the proportion of searches resulting in possible identifications from over half to a just 14%.

Profound Inequalities

Although the authorities refused to say what threshold is currently used, the recent NPL study found the system could generate incorrect matches for women of Black heritage almost 100 times more often than for white women at specific configurations.

The ministry commented on these findings: “The testing found that in a limited set of circumstances the software is more likely to wrongly flag some demographic groups in its search results.”

Balancing Utility and Fairness

Describing the impact of the brief increase to the system's accuracy setting, the police records state: “This adjustment significantly reduces the impact of discrimination across legally safeguarded attributes of race, generation and sex but had a significant negative impact on police efficiency”. The papers add that police units argued that “a once effective tactic returned results of questionable value”.

Broader Rollout Plans

Meanwhile, the UK administration has launched a ten-week consultation on its plans to expand the use of facial recognition technology. Policing minister Sarah Jones has described the technology as the “most significant advance since DNA matching”.

Criticism from Advisors and Monitors

Abimbola Johnson, chair of the advisory panel for the national policing equality strategy, commented: “There was scant discussion through equality strategy sessions of the facial recognition rollout even with clear relevance with the plan’s concerns.

“These revelations show once again that the anti-racism commitments the police has made via the race action plan are failing to be integrated into broader operations. Independent assessments have warned that new technologies are being rolled out in a landscape where ethnic inequalities, inadequate oversight and poor data collection already persist.

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

Official Statement

A government representative said: “The Home Office treat the findings of the report with utmost gravity and we have implemented changes. A updated software has been independently tested and acquired, 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 gamechanging technology will assist officers to apprehend and prosecute offenders. There is human involvement in every step of the procedure and no arrest or charge would be taken without specialist personnel meticulously examining the output.”