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Police forces across the UK effectively campaigned to deploy a facial recognition system known to be biased against females, youths, and members of ethnic minority groups, following complaints that a less biased version generated fewer potential suspects.

How the System Works

UK forces use the national police database to conduct retrospective facial recognition searches. This process entails matching a reference photograph of a person of interest against a repository of over 19 million mugshots to find potential matches.

Acknowledged Discrimination

The Home Office admitted last week that the technology was flawed. This acknowledgment came after a study by the government's National Physical Laboratory determined it incorrectly matched people of Black and Asian heritage and females at much greater frequency than white men. The Home Office stated it “had acted on the findings”.

“It prompts the issue of whether facial recognition only becomes useful if users tolerate biases in ethnicity and gender. Operational ease is a weak argument for disregarding fundamental rights.”

Long-Standing Problem

Official papers show that this bias has been known about 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 system's bias in September 2024. The Home Office-commissioned laboratory study found the system was had a higher probability to produce incorrect matches for photos of females, Black people, and those aged 40 and under.

A Reversed Decision

In reaction, the national police leadership body ordered that the confidence threshold 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 generating fewer “useful lines of inquiry”. Internal records show the higher threshold cut the number of queries that yielded possible identifications from over half to a just 14%.

Severe Disparities

Although the authorities declined to specify what threshold is currently used, the recent NPL study discovered the system could generate incorrect matches for Black women almost 100 times more often than for Caucasian women at specific configurations.

The ministry commented on these results: “The testing found that in a specific scenarios the algorithm is more likely to wrongly flag some demographic groups in its search results.”

Balancing Utility and Fairness

Outlining the effect of the temporary raise to the system's accuracy setting, the NPCC documents note: “This adjustment significantly reduces the impact of bias across protected characteristics of ethnicity, generation and gender but had a significant negative impact on operational effectiveness”. The papers add that forces argued that “a once effective tactic now delivered outcomes of limited benefit”.

Broader Rollout Plans

Meanwhile, the UK administration has launched a ten-week public review on its proposals to widen the use of facial recognition technology. Policing minister Sarah Jones has described the technology as the “most significant advance since genetic fingerprinting”.

Criticism from Advisors and Monitors

The chair of a police oversight board, head of the advisory panel for the national policing equality strategy, commented: “We observed scant consideration in equality strategy sessions of the technology deployment even with clear relevance with the plan’s concerns.

“This disclosure demonstrate once again that the pledges to combat discrimination the police has made through 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 racial disparities, inadequate oversight and poor data collection continue to exist.

“Any use of facial recognition must meet strict national standards, be independently scrutinised, and prove it reduces rather than compounds ethnic bias.”

Home Office Response

A government representative said: “We treat the findings of the study with utmost gravity and we have already taken action. A new algorithm has been independently tested and acquired, which has demonstrated no measurable discrimination. It will be tested early next year and will be undergo further assessment.

“Our priority is protecting the public. This gamechanging technology will support officers to apprehend and prosecute offenders. There is human involvement in every step of the process and no arrest or charge would be taken without trained officers meticulously examining the results.”