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Law enforcement agencies across the United Kingdom successfully lobbied to deploy a face scanning system acknowledged as discriminatory against females, young people, and members of ethnic minority groups, following complaints that a more accurate version produced a reduced number of potential suspects.

The Technology in Practice

UK forces use the national police database to carry out retrospective facial recognition searches. This process involves comparing a reference photograph of a person of interest against a repository of more than 19 million mugshots to find possible hits.

Admitted Bias

The Home Office admitted last week that the system was biased. This admission followed a study by the National Physical Laboratory (NPL) found it incorrectly matched Black and Asian people and females at much greater frequency than Caucasian males. The Home Office stated it “had acted on the findings”.

“This raises the issue of whether this technology only becomes useful if users accept biases in race and gender. Convenience is a weak argument for disregarding basic freedoms.”

Long-Standing Problem

Official papers show that this bias has been recognized for over twelve months. Furthermore, police forces lobbied to reverse an initial decision that was designed to mitigate the problem.

Senior officers were notified of the system's bias in late 2024. The government-ordered laboratory study found the system was more likely to suggest incorrect matches for images depicting females, Black people, and those aged 40 and under.

A Reversed Decision

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

However, this directive was overturned the following month following complaints from police that the modified technology was producing a lower number of “useful lines of inquiry”. Internal records indicate the higher threshold reduced the proportion of searches that yielded potential matches from over half to a just under 15%.

Severe Disparities

Although the Home Office and NPCC refused to say what threshold is now in operation, the latest independent review discovered the system could generate incorrect matches for Black women almost 100 times more often than for Caucasian women at certain settings.

The Home Office stated on these findings: “The testing found that in a specific scenarios the algorithm is more likely to wrongly flag some population segments in its match reports.”

Balancing Utility and Fairness

Outlining the impact of the brief increase to the system's confidence threshold, the NPCC documents note: “This adjustment greatly lessens the impact of bias across legally safeguarded attributes of race, age and sex but had a significant negative impact on police efficiency”. The papers further note that forces argued that “a previously useful tool returned results of questionable value”.

Broader Rollout Plans

Meanwhile, the UK administration has launched a two-and-a-half-month public review on its proposals to widen the use of biometric scanning systems. Policing minister the relevant minister has labeled the technology as the “biggest breakthrough since DNA matching”.

Criticism from Advisors and Monitors

The chair of a police oversight board, head of the independent scrutiny and oversight board for the national policing equality strategy, commented: “We observed very little discussion through equality strategy sessions of the technology deployment even with obvious cross-over with the strategy's goals.

“This disclosure demonstrate yet again that the pledges to combat discrimination the police has undertaken through the race action plan are not being translated into broader operations. Independent assessments have warned that new technologies are being implemented in a context where ethnic inequalities, weak scrutiny and poor data collection continue to exist.

“All deployment of facial recognition must adhere to rigorous official guidelines, be independently scrutinised, and prove it diminishes rather than compounds racial disparity.”

Official Statement

A government representative stated: “The Home Office treat the conclusions of the study seriously and we have implemented changes. 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 subject to evaluation.

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