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Police forces across the United Kingdom effectively campaigned to deploy a face scanning system known to be biased against females, youths, and members of ethnic minority groups, following complaints that a less biased version generated a reduced number of potential suspects.

How the System Works

UK forces use the police national database (PND) to carry out retrospective facial recognition searches. This procedure involves comparing a “probe image” of a suspect against a repository of more than 19 million custody photos to find potential matches.

Acknowledged Discrimination

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

“It prompts the question of whether this technology only becomes useful if users tolerate discrimination in ethnicity and gender. Convenience is a poor argument for disregarding fundamental rights.”

Long-Standing Problem

Internal documents show that this bias has been known about for over twelve months. Furthermore, law enforcement lobbied to reverse an initial decision that was intended to mitigate the problem.

Police bosses were informed of the system's bias in September 2024. The Home Office-commissioned laboratory study concluded the system was had a higher probability to suggest incorrect matches for images depicting females, Black people, and those under 40 years old.

A Reversed Decision

In reaction, the national police leadership body mandated that the accuracy setting required for possible hits be raised to a point where the bias was significantly reduced.

However, this directive was reversed the following month after forces complained that the adjusted system was producing a lower number of “useful lines of inquiry”. Internal records indicate the stricter setting reduced the number of queries resulting in potential matches from 56% to a mere 14%.

Severe Disparities

Although the Home Office and NPCC declined to specify what setting is now in operation, the latest independent review discovered the system could generate incorrect matches for women of Black heritage nearly a hundred times more often than for Caucasian women at certain settings.

The ministry stated on these results: “Our evaluation identified that in a specific scenarios the algorithm is has a greater tendency to wrongly flag some population segments in its match reports.”

Operational Effectiveness vs. Bias

Outlining the effect of the temporary raise to the system's confidence threshold, the NPCC documents note: “This adjustment greatly lessens the effect of bias across legally safeguarded attributes of ethnicity, age and gender but had a significant negative impact on police efficiency”. The papers add that police units argued that “a once effective tactic now delivered results of questionable value”.

Broader Rollout Plans

Meanwhile, the government has opened a two-and-a-half-month public review on its plans to widen the use of biometric scanning systems. Policing minister the relevant minister has described the technology as the “most significant advance since genetic fingerprinting”.

Criticism from Advisors and Monitors

Abimbola Johnson, chair of the independent scrutiny and oversight board for the police race action plan, said: “There was scant discussion in equality strategy sessions of the facial recognition rollout despite clear relevance with the plan’s concerns.

“These revelations show yet again that the pledges to combat discrimination policing has undertaken via the equality initiative are failing to be integrated into wider practice. Our reports have warned that innovative tools are being implemented in a landscape where ethnic inequalities, inadequate oversight and faulty information gathering already persist.

“Any use of facial recognition must meet rigorous official guidelines, be independently scrutinised, and prove it reduces rather than exacerbates ethnic bias.”

Home Office Response

A Home Office spokesperson stated: “The Home Office treat the findings of the report seriously and we have implemented changes. A updated software has been independently tested and acquired, which has demonstrated no measurable discrimination. It will be tested early next year and will be undergo evaluation.

“Our priority is protecting the public. This revolutionary tool will assist police to apprehend and prosecute offenders. There is human involvement in each stage of the process and no arrest or charge would be pursued without specialist personnel carefully reviewing the results.”