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Police forces across the United Kingdom successfully lobbied to use a facial recognition system known to be biased against women, young people, and members of ethnic minority groups, following complaints that a less biased version generated a reduced number of potential suspects.

The Technology in Practice

British police use the police national database (PND) to conduct searches using historical face recognition. This process entails matching a reference photograph of a suspect against a database of more than 19 million mugshots to identify potential matches.

Admitted Bias

The UK interior ministry conceded last week that the technology was flawed. This acknowledgment followed a review by the National Physical Laboratory (NPL) determined it incorrectly matched people of Black and Asian heritage and women at significantly higher rates than white men. The Home Office stated it “took steps on the findings”.

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

Known Issue

Internal documents reveal that this bias has been recognized for over twelve months. Furthermore, police forces lobbied to reverse an earlier ruling that was designed to mitigate 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 photos of females, individuals of Black ethnicity, and those aged 40 and under.

A Reversed Decision

In reaction, the national police leadership body mandated that the confidence threshold required for potential matches be raised to a level where the bias was significantly reduced.

However, this decision was reversed the next month following complaints from police that the adjusted system was generating fewer “useful lines of inquiry”. Internal records indicate the higher threshold cut the number of searches that yielded potential matches from over half to a just 14%.

Severe Disparities

Although the authorities declined to specify what setting is currently used, the latest NPL study found the system could generate incorrect matches for women of Black heritage almost 100 times more frequently than for white women at certain settings.

The Home Office commented on these findings: “The testing 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 brief increase to the system's accuracy setting, the police records state: “This adjustment greatly lessens the effect of bias across legally safeguarded attributes of race, generation and gender but had a substantially detrimental effect on operational effectiveness”. The papers add that police units complained that “a previously useful tool returned outcomes of limited benefit”.

Wider Implementation Proposals

Meanwhile, the government has launched a ten-week consultation on its proposals to widen the use of biometric scanning systems. The minister for police Sarah Jones has labeled the tool as the “biggest breakthrough since DNA matching”.

Criticism from Advisors and Monitors

Abimbola Johnson, head of the independent scrutiny and oversight board for the police race action plan, commented: “We observed scant consideration in equality strategy sessions of the facial recognition rollout even with obvious cross-over with the strategy's goals.

“This disclosure show once again that the anti-racism commitments policing has made via the race action plan are not being translated into broader operations. Independent assessments have cautioned that new technologies are being rolled out in a context where racial disparities, inadequate oversight and faulty information gathering continue to exist.

“All deployment of this technology must meet rigorous official guidelines, be independently scrutinised, and demonstrate it reduces rather than compounds racial disparity.”

Official Statement

A government representative stated: “The Home Office takes the findings of the report seriously and we have already taken action. A updated software has been independently tested and procured, which has no statistically significant bias. It will be tested early next year and will be undergo further assessment.

“Our priority is ensuring public safety. This gamechanging technology will support police to apprehend and prosecute offenders. There is human involvement in every step of the process and no further action would be pursued without specialist personnel carefully reviewing the results.”