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Police forces across the UK successfully lobbied to deploy a facial recognition system known to be biased against females, young people, and individuals from ethnic minority groups, after complaining that a more accurate version produced fewer potential suspects.

How the System Works

UK forces use the police national database (PND) to carry out searches using historical face recognition. This process involves comparing a “probe image” of a suspect against a repository of more than 19 million mugshots to find possible hits.

Admitted Bias

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

“This raises the issue of whether this technology only becomes effective if users accept discrimination in ethnicity and sex. Convenience is a poor argument for overriding fundamental rights.”

Known Issue

Official papers 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.

Senior officers were notified of the system's bias in late 2024. The Home Office-commissioned NPL review found the system was had a higher probability to produce false positives for images depicting females, individuals of Black ethnicity, and those aged 40 and under.

A Reversed Decision

In reaction, the national police leadership body mandated that the accuracy setting required for potential matches be increased to a level where the bias was significantly reduced.

However, this decision was reversed the following month following complaints from police that the modified technology was generating a lower number of “investigative leads”. NPCC documents show the higher threshold reduced the proportion of searches that yielded potential matches from over half to a mere 14%.

Profound Inequalities

Although the Home Office and NPCC declined to specify what setting is now in operation, the latest NPL study found the system could generate incorrect matches for women of Black heritage nearly a hundred times more often than for white women at certain settings.

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

Operational Effectiveness vs. Bias

Outlining the impact of the temporary raise to the system's accuracy setting, the NPCC documents note: “The change greatly lessens the effect of bias across legally safeguarded attributes of race, age and gender but had a significant negative impact on operational effectiveness”. The documents add that forces complained that “a previously useful tool now delivered results of limited benefit”.

Wider Implementation Proposals

Meanwhile, the UK administration has launched a ten-week consultation on its plans to widen the use of biometric scanning systems. The minister for police Sarah Jones has labeled the technology as the “biggest breakthrough since DNA matching”.

Expert and Oversight Concerns

Abimbola Johnson, head of the advisory panel for the national policing equality strategy, commented: “We observed scant discussion through equality strategy sessions of the technology deployment despite clear relevance with the plan’s concerns.

“This disclosure demonstrate yet again that the pledges to combat discrimination policing has made via the race action plan are not being translated into wider practice. Independent assessments have cautioned that innovative tools are being implemented in a context where ethnic inequalities, inadequate oversight and faulty information gathering already persist.

“All deployment of facial recognition must meet strict national standards, be subject to external review, and prove it reduces rather than compounds racial disparity.”

Home Office Response

A government representative stated: “The Home Office treat the findings of the report seriously and we have implemented changes. A new algorithm has been independently tested and procured, which has demonstrated no measurable discrimination. It will be trialled in the coming months and will be undergo evaluation.

“The foremost aim is protecting the public. This gamechanging technology will assist officers to put criminals and rapists behind bars. There is human involvement in each stage of the procedure and no arrest or charge would be taken without trained officers carefully reviewing the output.”