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Law enforcement agencies across the UK successfully lobbied to deploy a face scanning system known to be discriminatory against females, youths, and individuals from ethnic minority groups, after complaining that a less biased version produced a reduced number of investigative leads.

How the System Works

British police utilize the police national database (PND) to conduct retrospective facial recognition searches. This process involves comparing a “probe image” of a person of interest against a database of over 19 million mugshots to find potential matches.

Acknowledged Discrimination

The UK interior ministry conceded last week that the system was flawed. This admission followed a study by the National Physical Laboratory (NPL) found it incorrectly matched people of Black and Asian heritage and women at much greater frequency than white men. The Home Office said it “had acted on the findings”.

“This raises the issue of whether facial recognition only becomes useful if users accept biases in ethnicity and gender. Convenience is a poor argument for disregarding basic freedoms.”

Known Issue

Internal documents show that this bias has been recognized for more than a year. Furthermore, law enforcement lobbied to reverse an initial decision that was intended to address the problem.

Police bosses were informed of the system's bias in September 2024. The government-ordered NPL review concluded the system was had a higher probability to suggest false positives for photos of women, Black people, and those aged 40 and under.

A Reversed Decision

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

However, this decision was reversed the next month following complaints from police that the modified technology was generating fewer “investigative leads”. Internal records show the higher threshold cut the proportion of queries that yielded possible identifications from 56% to a just under 15%.

Severe Disparities

Although the Home Office and NPCC declined to specify what threshold is currently used, the recent NPL study found the system could produce false positives for Black women nearly a hundred times more frequently than for white women at specific configurations.

The Home Office stated on these results: “Our evaluation identified that in a specific scenarios the software is has a greater tendency to incorrectly include some population segments in its match reports.”

Balancing Utility and Fairness

Outlining the effect of the temporary raise to the system's confidence threshold, the NPCC documents state: “The change significantly reduces the impact of bias across legally safeguarded attributes of race, generation and sex but had a substantially detrimental effect on operational effectiveness”. The papers further note that police units complained that “a once effective tactic returned outcomes of questionable value”.

Wider Implementation Proposals

Meanwhile, the UK administration has launched a ten-week public review on its plans to widen the use of facial recognition technology. Policing minister Sarah Jones has labeled the technology as the “biggest breakthrough since genetic fingerprinting”.

Expert and Oversight Concerns

The chair of a police oversight board, head of the independent scrutiny and oversight board for the national policing equality strategy, commented: “We observed very little consideration through race action plan meetings of the technology deployment even with clear relevance with the plan’s concerns.

“This disclosure show once again that the pledges to combat discrimination the police has undertaken via the race action plan are failing to be integrated into wider practice. Our reports have cautioned that new technologies are being implemented in a landscape where racial disparities, inadequate oversight and faulty information gathering continue to exist.

“Any use of this technology must meet rigorous official guidelines, be independently scrutinised, and demonstrate it diminishes rather than compounds racial disparity.”

Official Statement

A Home Office spokesperson said: “We treat the findings of the report 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 trialled early next year and will be undergo further assessment.

“Our priority is ensuring public safety. This gamechanging technology will assist police to put criminals and rapists behind bars. There is officer review in every step of the procedure and no arrest or charge would be taken without specialist personnel meticulously examining the results.”