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Law enforcement agencies across the UK successfully lobbied to use a facial recognition system known to be biased against females, youths, and individuals from minority ethnic backgrounds, after complaining that a more accurate version generated a reduced number of potential suspects.

How the System Works

UK forces utilize the national police database to conduct retrospective facial recognition searches. This process entails matching a “probe image” of a suspect against a database of over 19 million mugshots to identify potential matches.

Acknowledged Discrimination

The Home Office admitted last week that the system was biased. This acknowledgment followed a study by the government's National Physical Laboratory determined it incorrectly matched people of Black and Asian heritage and females 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 effective if users tolerate biases in ethnicity and gender. Convenience is a weak argument for overriding basic freedoms.”

Long-Standing Problem

Internal documents reveal that this discriminatory flaw has been recognized for more than a year. Furthermore, law enforcement argued to overturn an earlier ruling that was intended to address the problem.

Senior officers were informed of the algorithmic discrimination in September 2024. The government-ordered laboratory study concluded the system was more likely to produce incorrect matches for photos of females, 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 increased to a level where the disparity was greatly diminished.

However, this directive was reversed the following month following complaints from police that the modified technology was generating fewer “useful lines of inquiry”. NPCC documents show the higher threshold cut the proportion of searches resulting in potential matches from over half to a mere 14%.

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 frequently than for white women at certain settings.

The ministry commented on these findings: “The testing found that in a limited set of circumstances the software is has a greater tendency to wrongly flag some population segments in its search results.”

Balancing Utility and Fairness

Describing the impact of the brief increase to the system's accuracy setting, the police records state: “This adjustment significantly reduces the impact of bias across protected characteristics of race, generation and sex but had a significant negative impact on operational effectiveness”. The documents add that police units complained that “a previously useful tool now delivered outcomes of questionable value”.

Wider Implementation Proposals

Meanwhile, the UK administration has opened a ten-week public review on its proposals to widen the use of biometric scanning systems. The minister for police Sarah Jones has described the tool as the “biggest breakthrough since genetic fingerprinting”.

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 scant consideration through race action plan meetings of the facial recognition rollout despite obvious cross-over with the plan’s concerns.

“These revelations show yet again that the anti-racism commitments policing has undertaken via the race action plan are not being translated into broader operations. Independent assessments have cautioned that new technologies are being implemented in a context where ethnic inequalities, weak scrutiny and poor data collection continue to exist.

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

Official Statement

A Home Office spokesperson stated: “The Home Office treat the findings of the study with utmost gravity and we have already taken action. A new algorithm has been externally evaluated and procured, which has no statistically significant bias. It will be tested in the coming months and will be undergo evaluation.

“The foremost aim is protecting the public. This revolutionary tool will assist officers to put criminals and rapists behind bars. There is human involvement in each stage of the process and no arrest or charge would be pursued without trained officers meticulously examining the results.”