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Law enforcement agencies across the UK successfully lobbied to use a face scanning system known to be discriminatory against women, youths, and individuals from minority ethnic backgrounds, following complaints that a more accurate version generated a reduced number of investigative leads.

How the System Works

UK forces utilize the police national database (PND) to conduct searches using historical face recognition. This process entails comparing a “probe image” of a person of interest against a repository of over 19 million custody photos to find potential matches.

Admitted Bias

The Home Office admitted last week that the technology was flawed. This acknowledgment came after a review by the National Physical Laboratory (NPL) determined it misidentified Black and Asian people and women at significantly higher rates than Caucasian males. The ministry stated it “had acted on the findings”.

“It prompts the question of whether this technology only becomes effective if users accept biases in race and sex. Convenience is a weak argument for overriding fundamental rights.”

Known Issue

Official papers show that this bias has been recognized for over twelve months. Furthermore, law enforcement lobbied to reverse an initial decision that was intended to mitigate the problem.

Senior officers were informed of the system's bias in late 2024. The Home Office-commissioned NPL review found the system was had a higher probability to produce incorrect matches for images depicting women, Black people, and those under 40 years old.

A Reversed Decision

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

However, this decision was overturned the next month following complaints from police that the adjusted system was producing fewer “useful lines of inquiry”. NPCC documents indicate the stricter setting cut the number of searches that yielded possible identifications from 56% 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 generate incorrect matches for women of Black heritage nearly a hundred times more frequently than for white women at specific configurations.

The Home Office stated on these results: “The testing identified that in a specific scenarios the software is more likely to wrongly flag some population segments in its match reports.”

Operational Effectiveness vs. Bias

Describing the effect of the brief increase to the system's confidence threshold, the NPCC documents note: “The change greatly lessens the impact of discrimination across legally safeguarded attributes of race, age and gender but had a substantially detrimental effect on operational effectiveness”. The papers add that police units complained that “a previously useful tool returned results of limited benefit”.

Wider Implementation Proposals

Meanwhile, the UK administration has opened a two-and-a-half-month public review on its plans to widen the use of biometric scanning systems. The minister for police the relevant minister has described the technology as the “biggest breakthrough since DNA matching”.

Criticism from Advisors and Monitors

Abimbola Johnson, head of the independent scrutiny and oversight board for the police race action plan, commented: “We observed very little consideration through equality strategy sessions of the facial recognition rollout even with clear relevance with the strategy's goals.

“This disclosure show yet again that the pledges to combat discrimination the police has made through the race action plan are failing to be integrated into wider practice. Our reports have warned that innovative tools are being rolled out in a landscape where racial disparities, weak scrutiny and poor data collection continue to exist.

“All deployment of this technology must meet rigorous official guidelines, be subject to external review, and demonstrate it reduces rather than exacerbates racial disparity.”

Home Office Response

A Home Office spokesperson stated: “We treat the conclusions of the study with utmost gravity and we have already taken action. A updated software has been externally evaluated and acquired, which has demonstrated no measurable discrimination. It will be trialled early next year and will be subject to evaluation.

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