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Law enforcement agencies across the UK successfully lobbied to use a facial recognition system known to be biased against females, young people, and members of minority ethnic backgrounds, after complaining that a less biased version produced fewer potential suspects.

How the System Works

UK forces use the police national database (PND) to conduct searches using historical face recognition. This process involves comparing a “probe image” of a suspect against a database of over 19 million custody photos to identify possible hits.

Admitted Bias

The Home Office conceded last week that the technology was biased. This acknowledgment followed a review by the government's National Physical Laboratory determined it misidentified Black and Asian people and females at significantly higher rates than white men. The ministry said it “took steps on the findings”.

“It prompts the issue of whether this technology only becomes effective if users tolerate biases in ethnicity and sex. Operational ease is a weak argument for overriding basic freedoms.”

Long-Standing Problem

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

Senior officers were informed of the algorithmic discrimination in late 2024. The Home Office-commissioned NPL review concluded the system was had a higher probability to produce false positives for photos of women, individuals of Black ethnicity, and those under 40 years old.

A Policy U-Turn

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

However, this directive was reversed the next month following complaints from police that the adjusted system was producing a lower number of “useful lines of inquiry”. Internal records indicate the stricter setting reduced the proportion of queries resulting in potential matches from 56% to a mere under 15%.

Profound Inequalities

Although the authorities declined to specify what setting is now in operation, the latest independent review discovered the system could generate false positives 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 identified that in a specific scenarios the algorithm is has a greater tendency to wrongly flag some population segments in its match reports.”

Operational Effectiveness vs. Bias

Outlining the effect of the temporary raise to the system's accuracy setting, the police records state: “This adjustment greatly lessens the effect of discrimination across legally safeguarded attributes of race, age and sex but had a substantially detrimental effect on operational effectiveness”. The papers further note that police units argued that “a once effective tactic returned outcomes of limited benefit”.

Wider Implementation Proposals

Meanwhile, the UK administration has launched a two-and-a-half-month public review on its plans to expand the use of biometric scanning systems. The minister for police the relevant minister has labeled the technology as the “most significant advance since DNA matching”.

Criticism from Advisors and Monitors

Abimbola Johnson, head of the independent scrutiny and oversight board for the national policing equality strategy, commented: “There was very little consideration through race action plan meetings of the technology deployment even with obvious cross-over with the strategy's goals.

“These revelations demonstrate yet again that the anti-racism commitments policing has undertaken through the equality initiative are failing to be integrated into broader operations. Independent assessments have warned that new technologies are being rolled out in a landscape where racial disparities, inadequate oversight and faulty information gathering already persist.

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

Home Office Response

A Home Office spokesperson stated: “The Home Office takes 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 tested in the coming months and will be undergo further assessment.

“The foremost aim is ensuring public safety. This gamechanging technology will assist police to apprehend and prosecute offenders. There is officer review in each stage of the procedure and no further action would be pursued without specialist personnel meticulously examining the output.”