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Law enforcement agencies across the UK effectively campaigned to deploy a facial recognition system known to be biased against females, young people, and members of minority ethnic backgrounds, after complaining that a more accurate version generated a reduced number of investigative leads.

The Technology in Practice

UK forces utilize the national police database to conduct searches using historical face recognition. This process entails comparing a “probe image” of a suspect against a repository of over 19 million custody photos to find possible hits.

Admitted Bias

The UK interior ministry conceded last week that the system was biased. This admission followed a review by the National Physical Laboratory (NPL) found it incorrectly matched people of Black and Asian heritage and females at much greater frequency than white men. The ministry said it “took steps on the findings”.

“This raises the question of whether this technology only becomes effective if users tolerate discrimination in race and gender. Operational ease is a poor argument for disregarding fundamental rights.”

Known Issue

Official papers reveal that this discriminatory flaw 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.

Police bosses were informed of the algorithmic discrimination in September 2024. The Home Office-commissioned NPL review found the system was had a higher probability to suggest incorrect matches for images depicting females, individuals of Black ethnicity, and those aged 40 and under.

A Policy U-Turn

In response, the National Police Chiefs’ Council (NPCC) ordered that the accuracy setting required for potential matches be increased to a point where the bias was greatly diminished.

However, this decision was reversed the following month following complaints from police that the modified technology was generating a lower number of “investigative leads”. Internal records indicate the higher threshold cut the number of searches resulting in possible identifications from over half to a just 14%.

Severe Disparities

Although the Home Office and NPCC declined to specify what setting is now in operation, the latest independent review discovered the system could produce false positives for Black women almost 100 times more often than for white women at specific configurations.

The ministry stated on these results: “Our evaluation found that in a limited set of circumstances the software is more likely to wrongly flag some population segments in its search results.”

Balancing Utility and Fairness

Describing the effect of the brief increase to the system's confidence threshold, the NPCC documents note: “This adjustment greatly lessens the impact of discrimination across protected characteristics of ethnicity, generation and sex but had a significant negative impact on operational effectiveness”. The papers further note that forces argued that “a previously useful tool returned results of questionable value”.

Wider Implementation Proposals

Meanwhile, the UK administration has launched a two-and-a-half-month public review on its proposals to widen the use of facial recognition technology. The minister for police the relevant minister has described the technology as the “most significant advance since DNA matching”.

Expert and Oversight Concerns

Abimbola Johnson, head of the advisory panel for the national policing equality strategy, commented: “There was scant discussion through race action plan meetings of the technology deployment even with clear relevance with the strategy's goals.

“This disclosure demonstrate once again that the anti-racism commitments policing has undertaken through the race action plan are failing to be integrated into broader operations. Our reports have cautioned that new technologies are being rolled out in a context where racial disparities, inadequate oversight and poor data collection already persist.

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

Home Office Response

A Home Office spokesperson said: “We takes the conclusions of the study seriously and we have implemented changes. A new algorithm has been externally evaluated and procured, which has demonstrated no measurable discrimination. It will be trialled in the coming months and will be undergo further assessment.

“Our priority is ensuring public safety. This gamechanging technology will support officers to put criminals and rapists behind bars. There is human involvement in every step of the procedure and no arrest or charge would be pursued without specialist personnel carefully reviewing the results.”