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Police forces across the United Kingdom effectively campaigned to use a face scanning system acknowledged as discriminatory against women, young people, and members of ethnic minority groups, after complaining that a less biased version produced a reduced number of potential suspects.

How the System Works

UK forces use the police national database (PND) to conduct retrospective facial recognition searches. This procedure involves matching a “probe image” of a suspect against a repository of more than 19 million mugshots to find possible hits.

Acknowledged Discrimination

The UK interior ministry conceded last week that the system was flawed. This acknowledgment followed a review by the government's National Physical Laboratory determined it misidentified Black and Asian people and females at significantly higher rates than Caucasian males. The ministry stated it “took steps on the findings”.

“It prompts the issue of whether facial recognition only becomes effective if users accept biases in ethnicity and gender. Convenience is a weak argument for overriding basic freedoms.”

Known Issue

Official papers reveal that this bias has been known about for over twelve months. Furthermore, law enforcement argued to overturn an earlier ruling that was intended to mitigate the problem.

Police bosses were informed of the system's bias in late 2024. The government-ordered NPL review concluded the system was had a higher probability to produce incorrect matches for images depicting women, Black people, and those under 40 years old.

A Policy U-Turn

In response, the national police leadership body mandated that the confidence threshold required for possible hits be increased to a point where the bias was significantly reduced.

However, this directive was overturned the next month following complaints from police that the adjusted system was producing fewer “useful lines of inquiry”. Internal records show the higher threshold reduced the proportion of queries that yielded possible identifications from over half to a mere under 15%.

Severe Disparities

Although the authorities refused to say what setting is currently used, the recent independent review discovered the system could produce false positives for Black women nearly a hundred times more frequently than for Caucasian women at specific configurations.

The Home Office stated on these findings: “The testing identified that in a limited set of circumstances the software is has a greater tendency to wrongly flag some demographic groups in its match reports.”

Balancing Utility and Fairness

Outlining the impact of the brief increase to the system's confidence threshold, the police records state: “This adjustment significantly reduces the effect of discrimination across protected characteristics of ethnicity, generation and sex but had a substantially detrimental effect on operational effectiveness”. The papers add that police units complained that “a previously useful tool now delivered results of limited benefit”.

Wider Implementation Proposals

Meanwhile, the government has launched a ten-week public review on its plans to widen the use of facial recognition technology. Policing minister the relevant minister has labeled the tool as the “biggest breakthrough since DNA matching”.

Criticism from Advisors and Monitors

Abimbola Johnson, chair of the independent scrutiny and oversight board for the police race action plan, said: “There was very little discussion in race action plan meetings of the technology deployment even with clear relevance with the plan’s concerns.

“These revelations show once again that the anti-racism commitments the police has made via the equality initiative are not being translated into wider practice. Our reports have warned that innovative tools are being rolled out in a landscape where ethnic inequalities, inadequate oversight and poor data collection continue to exist.

“Any use of this technology must adhere to rigorous official guidelines, be subject to external review, and demonstrate it diminishes rather than compounds racial disparity.”

Official Statement

A Home Office spokesperson said: “We treat the findings of the study seriously and we have implemented changes. A updated software has been independently tested and procured, which has no statistically significant bias. It will be tested early next year and will be undergo further assessment.

“Our priority is ensuring public safety. This revolutionary tool will assist officers to apprehend and prosecute offenders. There is human involvement in every step of the process and no further action would be taken without trained officers meticulously examining the output.”