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Law enforcement agencies across the UK effectively campaigned to deploy a facial recognition system known to be biased against women, young people, and members of minority ethnic backgrounds, following complaints that a less biased version produced fewer potential suspects.

The Technology in Practice

UK forces use the national police database to conduct retrospective facial recognition searches. This procedure involves matching a reference photograph of a person of interest against a database of more than 19 million mugshots to find potential matches.

Acknowledged Discrimination

The UK interior ministry admitted last week that the technology was biased. This admission followed a review by the government's National Physical Laboratory determined it incorrectly matched Black and Asian people and females at much greater frequency than Caucasian males. The ministry stated it “took steps on the findings”.

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

Long-Standing Problem

Internal documents show that this bias has been recognized for over twelve months. Furthermore, law enforcement lobbied to reverse an earlier ruling that was designed to address the problem.

Senior officers were notified of the system's bias in September 2024. The government-ordered NPL review concluded the system was had a higher probability to produce false positives for images depicting women, Black people, and those under 40 years old.

A Policy U-Turn

In response, the national police leadership body ordered that the accuracy setting required for potential matches be increased to a point where the disparity was greatly diminished.

However, this decision was overturned the following month following complaints from police that the adjusted system was generating fewer “investigative leads”. Internal records show the higher threshold cut the number of queries resulting in potential matches from over half to a just under 15%.

Profound Inequalities

Although the authorities refused to say what setting is currently used, the recent independent review found the system could produce false positives for Black women nearly a hundred times more frequently than for Caucasian women at specific configurations.

The ministry stated on these results: “The testing found that in a limited set of circumstances the algorithm is has a greater tendency to incorrectly include some population segments in its search results.”

Balancing Utility and Fairness

Describing the impact of the brief increase to the system's confidence threshold, the NPCC documents note: “This adjustment greatly lessens the effect of discrimination across protected characteristics of race, age and gender but had a significant negative impact on police efficiency”. The papers add that police units complained that “a once effective tactic returned results of questionable value”.

Wider Implementation Proposals

Meanwhile, the UK administration has opened a ten-week consultation on its plans to expand the use of biometric scanning systems. Policing minister the relevant minister has described the technology as the “most significant advance since genetic fingerprinting”.

Expert and Oversight Concerns

Abimbola Johnson, head of the advisory panel for the police race action plan, said: “There was scant discussion in race action plan meetings of the technology deployment even with clear relevance with the plan’s concerns.

“These revelations show yet again that the pledges to combat discrimination policing has made via the race action plan are not being translated into broader operations. Our reports have warned that innovative tools are being rolled out in a landscape where racial disparities, inadequate oversight and faulty information gathering already persist.

“All deployment of this technology must adhere to rigorous official guidelines, be subject to external review, and prove it diminishes rather than compounds racial disparity.”

Home Office Response

A Home Office spokesperson said: “The Home Office treat the conclusions of the report with utmost gravity and we have implemented changes. A new algorithm has been externally evaluated and procured, which has demonstrated no measurable discrimination. It will be trialled in the coming months and will be subject to further assessment.

“Our priority is ensuring public safety. This gamechanging technology will assist officers to apprehend and prosecute offenders. There is human involvement in every step of the process and no further action would be pursued without trained officers meticulously examining the results.”