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Police forces across the United Kingdom effectively campaigned to deploy a facial recognition system known to be discriminatory against women, youths, and individuals from minority ethnic backgrounds, following complaints that a less biased version produced a reduced number of investigative leads.

The Technology in Practice

UK forces use the police national database (PND) to conduct searches using historical face recognition. This procedure involves comparing a reference photograph of a suspect against a database of more than 19 million custody photos to identify possible hits.

Admitted Bias

The Home Office admitted last week that the system was biased. This admission came after a review by the government's National Physical Laboratory found it incorrectly matched people of Black and Asian heritage and females at much greater frequency than white men. The ministry said it “had acted on the findings”.

“This raises the issue of whether facial recognition only becomes effective if users tolerate discrimination in race and sex. Convenience is a poor argument for disregarding fundamental rights.”

Known Issue

Internal documents reveal that this discriminatory flaw has been known about for more than a year. Furthermore, police forces argued to overturn an initial decision that was intended to address the problem.

Senior officers were notified of the system's bias in September 2024. The Home Office-commissioned NPL review concluded the system was more likely to produce false positives for photos of women, Black people, and those aged 40 and under.

A Policy U-Turn

In response, the National Police Chiefs’ Council (NPCC) ordered that the confidence threshold required for potential matches be increased to a level where the bias was significantly reduced.

However, this decision was reversed the following month after forces complained that the adjusted system was generating fewer “useful lines of inquiry”. Internal records indicate the stricter setting cut the number of queries resulting in potential matches from over half to a mere under 15%.

Profound Inequalities

Although the authorities declined to specify what threshold is now in operation, the latest NPL study found the system could produce incorrect matches for Black women nearly a hundred times more often than for Caucasian women at certain settings.

The ministry commented on these findings: “Our evaluation found that in a specific scenarios the software is has a greater tendency to wrongly flag some population segments in its search results.”

Balancing Utility and Fairness

Outlining the impact of the temporary raise to the system's accuracy setting, the NPCC documents state: “The change significantly reduces the effect of bias across legally safeguarded attributes of ethnicity, age and gender but had a significant negative impact on operational effectiveness”. The papers add that police units argued that “a previously useful tool now delivered results of limited benefit”.

Wider Implementation Proposals

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

Criticism from Advisors and Monitors

The chair of a police oversight board, chair of the independent scrutiny and oversight board for the national policing equality strategy, said: “We observed very little consideration in equality strategy sessions of the facial recognition rollout even with obvious cross-over with the plan’s concerns.

“This disclosure demonstrate once again that the pledges to combat discrimination the police has made via the race action plan are not being translated into broader operations. Our reports have cautioned that innovative tools are being implemented in a landscape where ethnic inequalities, weak scrutiny and faulty information gathering already persist.

“All deployment of this technology must adhere to rigorous official guidelines, be independently scrutinised, and demonstrate it diminishes rather than exacerbates racial disparity.”

Official Statement

A government representative stated: “We takes the findings of the study seriously and we have already taken action. A new algorithm has been externally evaluated and acquired, which has demonstrated no measurable discrimination. It will be tested in the coming months and will be undergo further assessment.

“Our priority is protecting the public. This revolutionary tool will support officers to apprehend and prosecute offenders. There is officer review in each stage of the procedure and no further action would be taken without specialist personnel meticulously examining the output.”