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Law enforcement agencies across the UK effectively campaigned to deploy a face scanning system known to be biased against females, young people, and members of minority ethnic backgrounds, after complaining that a less biased version generated a reduced number of potential suspects.

The Technology in Practice

British police utilize the national police database to conduct retrospective facial recognition searches. This procedure involves matching a “probe image” of a suspect against a repository of more than 19 million mugshots to identify possible hits.

Admitted Bias

The Home Office conceded last week that the technology was flawed. This admission came after a review by the government's National Physical Laboratory found it misidentified Black and Asian people and women at significantly higher rates than white men. The ministry said it “had acted on the findings”.

“This raises the issue of whether this technology only becomes effective if users tolerate biases in ethnicity and sex. Operational ease is a weak argument for disregarding basic freedoms.”

Known Issue

Internal documents reveal that this bias has been known about for over twelve months. Furthermore, law enforcement lobbied to reverse an initial decision that was designed to address the problem.

Police bosses were notified of the algorithmic discrimination in late 2024. The government-ordered NPL review concluded the system was more likely to produce false positives for photos of women, individuals of Black ethnicity, and those under 40 years old.

A Policy U-Turn

In reaction, the National Police Chiefs’ Council (NPCC) mandated that the confidence threshold required for possible hits be increased to a point where the bias was significantly reduced.

However, this decision was overturned the next month after forces complained that the adjusted system was generating a lower number of “useful lines of inquiry”. NPCC documents show the stricter setting cut the number of queries that yielded possible identifications from 56% to a just under 15%.

Profound Inequalities

Although the authorities refused to say what threshold is currently used, the recent independent review discovered the system could generate incorrect matches for women of Black heritage almost 100 times more often than for white women at certain settings.

The ministry stated on these results: “Our evaluation found that in a limited set of circumstances the algorithm is has a greater tendency to incorrectly include some demographic groups in its match reports.”

Balancing Utility and Fairness

Outlining the impact of the temporary raise to the system's accuracy setting, the police records state: “This adjustment greatly lessens the impact of bias across protected characteristics of race, generation and sex but had a significant negative impact on police efficiency”. The documents add that forces argued that “a previously useful tool now delivered results of questionable value”.

Broader Rollout Plans

Meanwhile, the UK administration has launched a ten-week consultation on its proposals to expand the use of biometric scanning systems. The minister for police the relevant minister has labeled the technology as the “biggest breakthrough since genetic fingerprinting”.

Expert and Oversight Concerns

Abimbola Johnson, chair of the independent scrutiny and oversight board for the police race action plan, commented: “There was scant consideration through equality strategy sessions of the technology deployment even with obvious cross-over with the plan’s concerns.

“These revelations show once again that the pledges to combat discrimination policing has undertaken via the equality initiative are failing to be integrated into broader operations. Our reports have warned that innovative tools are being implemented in a context where racial disparities, inadequate oversight and poor data collection already persist.

“Any use of this technology must adhere to strict national standards, be independently scrutinised, and prove it reduces rather than exacerbates ethnic bias.”

Official Statement

A government representative stated: “The Home Office takes the conclusions of the report with utmost gravity and we have implemented changes. A new algorithm has been externally evaluated and procured, which has no statistically significant bias. It will be tested early next year and will be subject to evaluation.

“The foremost aim 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 further action would be taken without specialist personnel carefully reviewing the output.”