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Police forces across the UK successfully lobbied to use a facial recognition system acknowledged as biased against women, young people, and individuals from minority ethnic backgrounds, following complaints that a more accurate version produced fewer investigative leads.

How the System Works

British police utilize the police national database (PND) to carry out searches using historical face recognition. This procedure entails matching a “probe image” of a suspect against a repository of over 19 million mugshots to find potential matches.

Admitted Bias

The UK interior ministry conceded last week that the system was flawed. This admission followed a study by the National Physical Laboratory (NPL) found it misidentified Black and Asian people and females at significantly higher rates than Caucasian males. The ministry stated it “took steps on the findings”.

“This raises the question of whether facial recognition only becomes effective if users accept discrimination in race and sex. Convenience is a poor argument for overriding fundamental rights.”

Long-Standing Problem

Official papers show that this bias has been recognized for over twelve months. Furthermore, law enforcement argued to overturn an initial decision that was intended to mitigate the problem.

Police bosses were notified of the algorithmic discrimination in September 2024. The Home Office-commissioned laboratory study found the system was more likely to produce incorrect matches for photos of women, individuals of Black ethnicity, and those under 40 years old.

A Reversed Decision

In response, the national police leadership body mandated that the accuracy setting required for potential matches be increased to a point where the bias was significantly reduced.

However, this decision was overturned the next month following complaints from police that the modified technology was generating a lower number of “useful lines of inquiry”. NPCC documents show the stricter setting cut the number of searches resulting in potential matches from over half to a mere 14%.

Severe Disparities

Although the Home Office and NPCC declined to specify what threshold is now in operation, the recent independent review found the system could produce incorrect matches for Black women nearly a hundred times more often than for white women at specific configurations.

The Home Office stated on these results: “Our evaluation found that in a specific scenarios the software is has a greater tendency to incorrectly include some demographic groups in its search results.”

Operational Effectiveness vs. Bias

Outlining the effect of the temporary raise to the system's confidence threshold, the police records state: “The change greatly lessens the effect of discrimination across protected characteristics of race, generation and gender but had a substantially detrimental effect on police efficiency”. The documents add that forces argued that “a previously useful tool now delivered results of questionable value”.

Broader Rollout Plans

Meanwhile, the government has opened a two-and-a-half-month consultation on its proposals to expand the use of biometric scanning systems. Policing minister Sarah Jones has described the technology as the “most significant advance since DNA matching”.

Criticism from Advisors and Monitors

The chair of a police oversight board, chair of the advisory panel for the national policing equality strategy, commented: “There was scant consideration through race action plan meetings of the facial recognition rollout even with obvious cross-over with the plan’s concerns.

“These revelations show yet again that the anti-racism commitments policing has made via the race action plan are failing to be integrated into wider practice. Our reports have cautioned that innovative tools are being rolled out in a context where racial disparities, weak scrutiny and faulty information gathering continue to exist.

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

Official Statement

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 externally evaluated and procured, which has demonstrated no measurable discrimination. It will be trialled early next year and will be subject to evaluation.

“Our priority is protecting the public. This gamechanging technology will assist officers to put criminals and rapists behind bars. There is human involvement in each stage of the process and no arrest or charge would be pursued without trained officers meticulously examining the results.”