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Law enforcement agencies across the UK effectively campaigned to use a face scanning system known to be biased against women, youths, and individuals from minority ethnic backgrounds, following complaints that a less biased version produced a reduced number of potential suspects.

How the System Works

UK forces utilize the national police database to conduct retrospective facial recognition searches. This procedure involves comparing a reference photograph of a suspect against a database of more than 19 million mugshots to identify possible hits.

Admitted Bias

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

“This raises the question of whether facial recognition only becomes effective if users accept biases in race and sex. Convenience is a weak argument for overriding fundamental rights.”

Long-Standing Problem

Internal documents show that this bias has been recognized for more than a year. Furthermore, law enforcement lobbied to reverse an earlier ruling that was intended to mitigate 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 suggest incorrect matches for photos of females, Black people, and those aged 40 and under.

A Reversed Decision

In reaction, the National Police Chiefs’ Council (NPCC) ordered 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 after forces complained that the modified technology was producing a lower number of “useful lines of inquiry”. NPCC documents show the higher threshold reduced the proportion of searches that yielded possible identifications from over half to a just 14%.

Profound Inequalities

Although the authorities refused to say what threshold is currently used, the recent independent review found the system could produce incorrect matches for Black women nearly a hundred times more often than for Caucasian women at certain settings.

The Home Office commented on these results: “Our evaluation identified that in a limited set of circumstances the algorithm is has a greater tendency to incorrectly include some population segments in its match reports.”

Balancing Utility and Fairness

Describing the impact of the temporary raise to the system's confidence threshold, the police records note: “The change significantly reduces the effect of discrimination across legally safeguarded attributes of race, age and gender but had a significant negative impact on police efficiency”. The documents further note that forces complained that “a previously useful tool now delivered results of questionable value”.

Broader Rollout Plans

Meanwhile, the UK administration has opened a two-and-a-half-month consultation on its proposals to expand the use of facial recognition technology. Policing minister the relevant minister has described the technology as the “biggest breakthrough since genetic fingerprinting”.

Expert and Oversight Concerns

Abimbola Johnson, chair of the independent scrutiny and oversight board for the police race action plan, said: “We observed very little discussion in equality strategy sessions of the facial recognition rollout even with obvious cross-over with the plan’s concerns.

“These revelations show once again that the pledges to combat discrimination the police has made through the race action plan are failing to be integrated into wider practice. Our reports have cautioned that innovative tools are being rolled out in a landscape where ethnic inequalities, weak scrutiny and faulty information gathering already persist.

“Any use 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 said: “We treat the conclusions of the study seriously and we have implemented changes. A updated software has been externally evaluated and acquired, which has no statistically significant bias. It will be trialled early next year and will be subject to further assessment.

“Our priority is ensuring public safety. This revolutionary tool will support officers to put criminals and rapists behind bars. There is officer review in each stage of the procedure and no further action would be taken without specialist personnel meticulously examining the results.”