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Police forces across the UK successfully lobbied to use a face scanning system known to be biased against women, youths, and individuals from ethnic minority groups, after complaining that a more accurate version produced a reduced number of potential suspects.

The Technology in Practice

British police use the national police database to carry out retrospective facial recognition searches. This procedure involves matching a “probe image” of a suspect against a repository of over 19 million mugshots to identify possible hits.

Acknowledged Discrimination

The Home Office conceded last week that the system was flawed. This acknowledgment followed a review by the National Physical Laboratory (NPL) found it misidentified people of Black and Asian heritage and females at significantly higher rates than Caucasian males. The ministry stated it “took steps on the findings”.

“This raises the issue of whether facial recognition only becomes useful if users accept discrimination in race and gender. Operational ease is a weak argument for overriding fundamental rights.”

Known Issue

Official papers show that this discriminatory flaw has been recognized for over twelve months. Furthermore, police forces argued to overturn an earlier ruling that was intended to address the problem.

Police bosses were informed of the algorithmic discrimination in late 2024. The Home Office-commissioned laboratory study found the system was had a higher probability to produce incorrect matches for images depicting women, individuals of Black ethnicity, and those under 40 years old.

A Policy U-Turn

In response, the National Police Chiefs’ Council (NPCC) mandated that the confidence threshold required for potential matches be raised to a point where the disparity was significantly reduced.

However, this decision was reversed the next month following complaints from police that the modified technology was generating a lower number of “useful lines of inquiry”. Internal records show the higher threshold reduced the number of queries resulting in possible identifications from over half to a mere under 15%.

Profound Inequalities

Although the authorities refused to say what threshold is currently used, the latest independent review discovered the system could produce incorrect matches for Black women nearly a hundred times more frequently than for white women at specific configurations.

The Home Office stated on these findings: “The testing identified that in a specific scenarios the software is has a greater tendency to incorrectly include some population segments in its match reports.”

Balancing Utility and Fairness

Describing the effect of the brief increase to the system's confidence threshold, the police records note: “This adjustment significantly reduces the impact of bias across protected characteristics of race, age and gender but had a significant negative impact on police efficiency”. The papers further note that forces argued that “a once effective tactic now delivered outcomes of questionable value”.

Broader Rollout Plans

Meanwhile, the government has launched a ten-week consultation on its plans to expand the use of facial recognition technology. The minister for police the relevant minister has labeled the tool as the “biggest breakthrough since DNA matching”.

Expert and Oversight Concerns

The chair of a police oversight board, head of the advisory panel for the police race action plan, said: “We observed scant discussion in equality strategy sessions of the technology deployment even with clear relevance with the strategy's goals.

“This disclosure show yet again that the anti-racism commitments the police has undertaken through the race action plan are not being translated into wider practice. Our reports have warned that innovative tools are being implemented in a landscape where ethnic inequalities, weak scrutiny and poor data collection continue to exist.

“Any use of facial recognition must adhere to rigorous official guidelines, be independently scrutinised, and demonstrate it reduces rather than exacerbates racial disparity.”

Official Statement

A Home Office spokesperson said: “The Home Office takes the conclusions of the report with utmost gravity and we have already taken action. A new algorithm has been externally evaluated and acquired, which has demonstrated no measurable discrimination. It will be trialled early next year and will be undergo evaluation.

“Our priority is protecting the public. This revolutionary tool will assist officers to apprehend and prosecute offenders. There is officer review in each stage of the procedure and no arrest or charge would be pursued without specialist personnel carefully reviewing the results.”