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Law enforcement agencies across the United Kingdom effectively campaigned to use a face scanning system known to be biased against women, young people, and individuals from minority ethnic backgrounds, after complaining that a more accurate version generated a reduced number of potential suspects.

The Technology in Practice

UK forces use the national police database to conduct searches using historical face recognition. This process entails matching a “probe image” of a person of interest against a database of more than 19 million custody photos to identify potential matches.

Admitted Bias

The UK interior ministry conceded last week that the system was biased. This admission came after a study by the National Physical Laboratory (NPL) found it misidentified Black and Asian people and females at significantly higher rates than white men. The ministry stated it “took steps on the findings”.

“This raises the issue of whether facial recognition only becomes effective if users tolerate biases in ethnicity and sex. Convenience is a weak argument for overriding fundamental rights.”

Long-Standing Problem

Internal documents reveal that this discriminatory flaw has been recognized for more than a year. Furthermore, police forces lobbied to reverse an initial decision that was intended to mitigate the problem.

Police bosses were informed of the algorithmic discrimination in September 2024. The government-ordered laboratory study found the system was had a higher probability to suggest false positives for images depicting women, Black people, and those under 40 years old.

A Policy U-Turn

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

However, this directive was reversed the following month after forces complained that the modified technology was producing a lower number of “investigative leads”. NPCC documents indicate the higher threshold cut the number of searches that yielded potential matches from over half to a mere 14%.

Severe Disparities

Although the authorities refused to say what threshold is currently used, the latest independent review 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 Home Office stated on these results: “Our evaluation identified that in a specific scenarios the algorithm is more likely to wrongly flag some population segments in its match reports.”

Operational Effectiveness vs. Bias

Outlining the impact of the brief increase to the system's confidence threshold, the police records state: “The change greatly lessens the effect of discrimination across protected characteristics of ethnicity, age and sex but had a substantially detrimental effect on operational effectiveness”. The documents add that forces complained that “a previously useful tool returned results of limited benefit”.

Broader Rollout Plans

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

Expert and Oversight Concerns

Abimbola Johnson, head of the advisory panel for the police race action plan, said: “We observed scant consideration in race action plan meetings of the technology deployment even with obvious cross-over with the plan’s concerns.

“This disclosure show yet again that the anti-racism commitments the police has made through the equality initiative are failing to be integrated into broader operations. Our reports have warned that innovative tools are being implemented in a landscape where racial disparities, inadequate oversight and poor data collection continue to exist.

“All deployment of this technology must meet strict national standards, be independently scrutinised, and demonstrate it reduces rather than compounds ethnic bias.”

Official Statement

A government representative said: “The Home Office treat the conclusions of the report seriously and we have already taken action. A new algorithm has been independently tested and acquired, which has demonstrated no measurable discrimination. It will be trialled early next year and will be undergo evaluation.

“The foremost aim is protecting the public. This gamechanging technology will support officers 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 trained officers carefully reviewing the output.”