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Law enforcement agencies across the United Kingdom effectively campaigned to use a face scanning system known to be discriminatory against females, young people, and members of ethnic minority groups, after complaining that a more accurate version produced fewer investigative leads.

How the System Works

British police use the national police database to carry out searches using historical face recognition. This procedure involves comparing a reference photograph of a person of interest against a repository of more than 19 million mugshots to find potential matches.

Admitted Bias

The UK interior ministry conceded last week that the technology was flawed. This acknowledgment followed a study by the National Physical Laboratory (NPL) found it misidentified people of Black and Asian heritage and females at much greater frequency than white men. The ministry stated it “had acted on the findings”.

“It prompts the issue of whether this technology only becomes effective if users tolerate biases in race and gender. Convenience is a weak argument for overriding fundamental rights.”

Long-Standing Problem

Official papers reveal that this bias has been known about for more than a year. Furthermore, law enforcement argued to overturn an initial decision that was intended to address the problem.

Police bosses were informed of the system's bias in late 2024. The Home Office-commissioned laboratory study concluded the system was more likely to suggest false positives for photos of women, Black people, and those under 40 years old.

A Reversed Decision

In response, the National Police Chiefs’ Council (NPCC) ordered that the confidence threshold required for potential matches be increased to a level where the bias was greatly diminished.

However, this decision was reversed the following month following complaints from police that the adjusted system was generating fewer “investigative leads”. NPCC documents indicate the higher threshold reduced the proportion of queries that yielded potential matches from over half to a just under 15%.

Profound Inequalities

Although the authorities refused to say what threshold is currently used, the latest NPL study discovered the system could generate incorrect matches for women of Black heritage nearly a hundred times more frequently than for Caucasian women at specific configurations.

The Home Office commented on these results: “The testing identified that in a specific scenarios the software is more likely to wrongly flag some demographic groups in its match reports.”

Balancing Utility and Fairness

Describing the effect of the temporary raise to the system's accuracy setting, the NPCC documents note: “This adjustment greatly lessens the impact of bias across protected characteristics of ethnicity, age and gender but had a significant negative impact on operational effectiveness”. The documents further note that police units argued that “a previously useful tool returned outcomes of questionable value”.

Wider Implementation Proposals

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

Expert and Oversight Concerns

Abimbola Johnson, chair of the independent scrutiny and oversight board for the police race action plan, commented: “We observed scant discussion through race action plan meetings of the facial recognition rollout despite clear relevance with the strategy's goals.

“This disclosure demonstrate yet again that the anti-racism commitments the police has made via the race action plan are not being translated into wider practice. Our reports have cautioned that innovative tools are being rolled out in a context where ethnic inequalities, weak scrutiny and poor data collection continue to exist.

“All deployment of facial recognition must adhere to rigorous official guidelines, be independently scrutinised, and prove it diminishes rather than exacerbates racial disparity.”

Official Statement

A Home Office spokesperson stated: “We takes the findings of the study with utmost gravity and we have implemented changes. A updated software has been externally evaluated and procured, which has no statistically significant bias. It will be tested early next year and will be undergo further assessment.

“The foremost aim is ensuring public safety. This revolutionary tool will assist police to put criminals and rapists behind bars. There is officer review in each stage of the process and no arrest or charge would be pursued without trained officers meticulously examining the output.”