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Police forces across the United Kingdom effectively campaigned to use a face scanning system acknowledged as biased against women, young people, and individuals from minority ethnic backgrounds, following complaints that a less biased version produced a reduced number of investigative leads.

How the System Works

UK forces use the police national database (PND) to conduct retrospective facial recognition searches. This procedure involves matching a reference photograph of a suspect against a database of over 19 million mugshots to find potential matches.

Acknowledged Discrimination

The UK interior ministry conceded last week that the technology was flawed. This acknowledgment came after a study by the government's National Physical Laboratory found it misidentified Black and Asian people and women at significantly higher rates than Caucasian males. The Home Office said it “had acted on the findings”.

“It prompts the issue of whether this technology only becomes useful if users tolerate biases in race and sex. Operational ease is a poor argument for overriding fundamental rights.”

Known Issue

Internal documents reveal that this discriminatory flaw has been recognized for over twelve months. Furthermore, law enforcement lobbied to reverse an earlier ruling that was intended to address the problem.

Police bosses were notified of the system's bias in late 2024. The Home Office-commissioned NPL review found the system was had a higher probability to suggest incorrect matches for photos of females, individuals of Black ethnicity, and those aged 40 and under.

A Reversed Decision

In response, the National Police Chiefs’ Council (NPCC) mandated that the confidence threshold required for possible hits be increased to a point where the bias was significantly reduced.

However, this directive was reversed the next month following complaints from police that the adjusted system was producing fewer “useful lines of inquiry”. Internal records indicate the higher threshold cut the proportion of searches resulting in potential matches from 56% to a just 14%.

Severe Disparities

Although the Home Office and NPCC declined to specify what threshold is currently used, the latest independent review discovered the system could generate false positives for women of Black heritage almost 100 times more often than for Caucasian women at certain settings.

The ministry stated on these results: “The testing found that in a specific scenarios the algorithm is more likely to wrongly flag some population segments in its match reports.”

Balancing Utility and Fairness

Outlining the impact of the brief increase to the system's accuracy setting, the police records state: “This adjustment greatly lessens the impact of bias across protected characteristics of race, generation and gender but had a significant negative impact on operational effectiveness”. The papers add that police units argued that “a once effective tactic now delivered results of limited benefit”.

Broader Rollout Plans

Meanwhile, the UK administration has launched a two-and-a-half-month consultation on its proposals to widen the use of facial recognition technology. The minister for police Sarah Jones has described the technology as the “biggest breakthrough since genetic fingerprinting”.

Criticism from Advisors and Monitors

Abimbola Johnson, head of the advisory panel for the national policing equality strategy, commented: “There was scant consideration through equality strategy sessions of the facial recognition rollout despite obvious cross-over with the plan’s concerns.

“These revelations demonstrate yet again that the pledges to combat discrimination policing has made via the equality initiative are not being translated into wider practice. Our reports have warned that new technologies are being implemented in a landscape where racial disparities, inadequate oversight and faulty information gathering continue to exist.

“All deployment of this technology must adhere to strict national standards, be independently scrutinised, and demonstrate it diminishes rather than exacerbates racial disparity.”

Home Office Response

A Home Office spokesperson stated: “We takes the conclusions of the study seriously 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 gamechanging technology will support officers to put criminals and rapists behind bars. There is officer review in each stage of the process and no further action would be pursued without trained officers meticulously examining the output.”