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Law enforcement agencies across the United Kingdom successfully lobbied to deploy a facial recognition system known to be biased against women, young people, and individuals from ethnic minority groups, following complaints that a more accurate version generated fewer investigative leads.

The Technology in Practice

British police use the police national database (PND) to carry out searches using historical face recognition. This process involves matching a reference photograph of a suspect against a database of more than 19 million custody photos to find possible hits.

Admitted Bias

The Home Office conceded last week that the technology was biased. This acknowledgment came after a review by the National Physical Laboratory (NPL) found it incorrectly matched people of Black and Asian heritage and women at much greater frequency than Caucasian males. The Home Office stated it “took steps on the findings”.

“This raises the question of whether facial recognition only becomes useful if users tolerate discrimination in ethnicity and sex. Operational ease is a weak argument for overriding basic freedoms.”

Known Issue

Internal documents show that this bias has been known about for more than a year. Furthermore, law enforcement lobbied to reverse an earlier ruling that was designed to mitigate the problem.

Police bosses were informed of the algorithmic discrimination in late 2024. The government-ordered laboratory study concluded the system was more likely to produce incorrect matches for images depicting women, individuals of Black ethnicity, and those under 40 years old.

A Reversed Decision

In reaction, the national police leadership body mandated that the accuracy setting required for possible hits be increased to a level where the disparity was greatly diminished.

However, this decision was reversed the following month following complaints from police that the modified technology was producing a lower number of “investigative leads”. NPCC documents indicate the stricter setting cut the proportion of searches resulting in potential matches from 56% to a mere under 15%.

Severe Disparities

Although the authorities refused to say what threshold is now in operation, the latest independent review found the system could produce false positives for Black women almost 100 times more frequently than for Caucasian women at specific configurations.

The Home Office stated on these results: “Our evaluation identified that in a specific scenarios the algorithm is has a greater tendency to wrongly flag some demographic groups in its match reports.”

Balancing Utility and Fairness

Outlining the impact of the temporary raise to the system's accuracy setting, the NPCC documents state: “The change greatly lessens the impact of bias across protected characteristics of ethnicity, generation and sex but had a substantially detrimental effect on police efficiency”. The documents further note that police units argued that “a previously useful tool now delivered outcomes of limited benefit”.

Broader Rollout Plans

Meanwhile, the UK administration has opened a ten-week public review on its plans to widen the use of biometric scanning systems. The minister for police Sarah Jones has described the technology as the “biggest breakthrough since genetic fingerprinting”.

Criticism from Advisors and Monitors

The chair of a police oversight board, chair of the advisory panel for the police race action plan, said: “There was scant discussion in race action plan meetings of the technology deployment even with obvious cross-over with the plan’s concerns.

“These revelations demonstrate once again that the anti-racism commitments policing has undertaken via the equality initiative are failing to be integrated into broader operations. Our reports have cautioned that innovative tools are being rolled out in a context where ethnic inequalities, inadequate oversight and faulty information gathering continue to exist.

“Any use of facial recognition must meet rigorous official guidelines, be subject to external review, and prove it diminishes rather than compounds ethnic bias.”

Official Statement

A Home Office spokesperson stated: “We takes the findings of the report seriously and we have implemented changes. A new algorithm has been independently tested and acquired, which has demonstrated no measurable discrimination. It will be trialled in the coming months and will be subject to further assessment.

“Our priority is protecting the public. 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 further action would be pursued without trained officers meticulously examining the results.”