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Law enforcement agencies across the UK successfully lobbied to use a face scanning system known to be discriminatory against women, young people, and individuals from minority ethnic backgrounds, following complaints that a more accurate version produced fewer investigative leads.

How the System Works

British police use the national police database to conduct retrospective facial recognition searches. This process entails comparing a reference photograph of a suspect against a database of more than 19 million custody photos to find possible hits.

Admitted Bias

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

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

Long-Standing Problem

Internal documents show that this discriminatory flaw has been known about for over twelve months. Furthermore, law enforcement argued to overturn an earlier ruling that was intended to address the problem.

Police bosses were informed of the system's bias in late 2024. The government-ordered NPL review found the system was had a higher probability to suggest false positives for photos of women, Black people, and those under 40 years old.

A Policy U-Turn

In response, the National Police Chiefs’ Council (NPCC) ordered that the confidence threshold required for possible hits be raised to a point where the bias was greatly diminished.

However, this decision was reversed the next month after forces complained that the adjusted system was producing fewer “useful lines of inquiry”. Internal records show the stricter setting reduced the number of queries that yielded potential matches from 56% to a just under 15%.

Profound Inequalities

Although the Home Office and NPCC refused to say what setting is currently used, the latest NPL study discovered the system could produce false positives for women of Black heritage almost 100 times more frequently than for Caucasian women at specific configurations.

The Home Office stated on these results: “Our evaluation found that in a specific scenarios the software is more likely to incorrectly include some population segments in its match reports.”

Operational Effectiveness vs. Bias

Describing the impact of the temporary raise to the system's confidence threshold, the NPCC documents note: “This adjustment significantly reduces the effect of bias across protected characteristics of race, generation and gender but had a significant negative impact on operational effectiveness”. The papers add that police units argued that “a once effective tactic now delivered outcomes of questionable value”.

Broader Rollout Plans

Meanwhile, the UK administration has launched a two-and-a-half-month consultation on its plans to widen the use of biometric scanning systems. Policing minister the relevant minister has described the tool as the “biggest breakthrough since genetic fingerprinting”.

Expert and Oversight Concerns

Abimbola Johnson, chair of the independent scrutiny and oversight board for the national policing equality strategy, said: “We observed very little consideration through equality strategy sessions of the facial recognition rollout despite clear relevance with the strategy's goals.

“These revelations show once again that the anti-racism commitments policing has made through the equality initiative are not being translated into broader operations. Our reports have cautioned that innovative tools are being implemented in a landscape where racial disparities, weak scrutiny and poor data collection continue to exist.

“Any use of facial recognition must adhere to strict national standards, be subject to external review, and prove it diminishes rather than exacerbates ethnic bias.”

Home Office Response

A government representative said: “The Home Office treat the conclusions of the study seriously and we have implemented changes. 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 subject to further assessment.

“Our priority is protecting the public. This revolutionary tool will assist officers to put criminals and rapists behind bars. There is human involvement in every step of the process and no further action would be taken without specialist personnel carefully reviewing the results.”