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Law enforcement agencies across the UK effectively campaigned to use a facial recognition system acknowledged as biased against women, youths, and members of minority ethnic backgrounds, following complaints that a less biased version generated fewer potential suspects.

The Technology in Practice

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

Acknowledged Discrimination

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

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

Long-Standing Problem

Internal documents reveal that this discriminatory flaw has been known about for over twelve months. Furthermore, police forces lobbied to reverse an earlier ruling that was intended to address the problem.

Senior officers were notified of the system's bias in late 2024. The Home Office-commissioned laboratory study concluded the system was had a higher probability to suggest incorrect matches for images depicting women, Black people, and those aged 40 and under.

A Policy U-Turn

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

However, this decision was reversed the following month following complaints from police that the modified technology was generating a lower number of “useful lines of inquiry”. NPCC documents show the stricter setting reduced the proportion of queries resulting in possible identifications from 56% to a mere under 15%.

Profound Inequalities

Although the authorities declined to specify what threshold is currently used, the latest independent review discovered the system could produce false positives for women of Black heritage almost 100 times more often than for white women at certain settings.

The Home Office commented on these results: “The testing 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 impact of the temporary raise to the system's confidence threshold, the NPCC documents state: “The change significantly reduces the effect of bias across legally safeguarded attributes of race, age and gender but had a significant negative impact on police efficiency”. The documents add that police units complained that “a once effective tactic now delivered outcomes of limited benefit”.

Wider Implementation Proposals

Meanwhile, the government has launched a ten-week public review on its plans to widen the use of facial recognition technology. Policing minister the relevant minister has described the tool as the “biggest breakthrough since genetic fingerprinting”.

Criticism from Advisors and Monitors

Abimbola Johnson, head of the independent scrutiny and oversight board for the police race action plan, said: “There was very little discussion in equality strategy sessions of the facial recognition rollout despite clear relevance with the strategy's goals.

“This disclosure demonstrate yet again that the pledges to combat discrimination the police has made through the race action plan are not being translated into wider practice. Independent assessments have cautioned that new technologies are being rolled out 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 subject to external review, and prove it diminishes rather than compounds ethnic bias.”

Home Office Response

A government representative said: “The Home Office takes the findings 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 in the coming months and will be subject to further assessment.

“The foremost aim is protecting the public. This revolutionary tool will support police to apprehend and prosecute offenders. There is officer review in every step of the procedure and no arrest or charge would be pursued without trained officers meticulously examining the output.”