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Law enforcement agencies across the United Kingdom effectively campaigned to use a facial recognition system acknowledged as biased against women, young people, and members of minority ethnic backgrounds, after complaining that a less biased version produced fewer potential suspects.

The Technology in Practice

UK forces utilize the police national database (PND) to conduct retrospective facial recognition searches. This procedure entails matching a “probe image” of a person of interest against a repository of more than 19 million mugshots to find potential matches.

Admitted Bias

The Home Office conceded 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 significantly higher rates than white men. The ministry stated it “had acted on the findings”.

“This raises the issue of whether facial recognition only becomes effective if users tolerate biases in ethnicity and gender. Convenience is a weak argument for disregarding basic freedoms.”

Known Issue

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 designed to mitigate the problem.

Police bosses were notified of the algorithmic discrimination in late 2024. The government-ordered NPL review concluded the system was had a higher probability to suggest false positives for photos of women, Black people, and those under 40 years old.

A Policy U-Turn

In reaction, the National Police Chiefs’ Council (NPCC) mandated that the confidence threshold required for possible hits be raised to a point where the bias was greatly diminished.

However, this decision was reversed 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 cut the proportion of searches resulting in potential matches from over half to a mere 14%.

Severe Disparities

Although the authorities refused to say what setting is currently used, the recent NPL study discovered the system could produce false positives for women of Black heritage nearly a hundred times more frequently than for white women at certain settings.

The ministry stated on these findings: “The testing identified that in a specific scenarios the algorithm is has a greater tendency to incorrectly include some population segments in its match reports.”

Balancing Utility and Fairness

Outlining the effect of the temporary raise to the system's accuracy setting, the NPCC documents note: “The change greatly lessens the effect of bias across protected characteristics 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 returned results of questionable value”.

Broader Rollout Plans

Meanwhile, the UK administration has launched a two-and-a-half-month consultation on its plans to widen the use of facial recognition technology. Policing minister the relevant minister has described the tool as the “biggest breakthrough since DNA matching”.

Expert and Oversight Concerns

Abimbola Johnson, head of the independent scrutiny and oversight board for the national policing equality strategy, commented: “We observed very little discussion in equality strategy sessions of the technology deployment despite clear relevance with the plan’s concerns.

“These revelations show once again that the pledges to combat discrimination policing has made via the equality initiative are not being translated into wider practice. Independent assessments have cautioned that innovative tools are being implemented in a landscape 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: “We treat the findings of the study seriously and we have already taken action. A new algorithm has been independently tested and procured, which has demonstrated no measurable discrimination. It will be tested in the coming months and will be undergo further assessment.

“The foremost aim is protecting the public. This gamechanging technology will assist police to put criminals and rapists behind bars. There is human involvement in each stage of the process and no arrest or charge would be taken without trained officers carefully reviewing the output.”