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Police forces across the United Kingdom effectively campaigned to deploy a facial recognition system acknowledged as biased against females, young people, and individuals from ethnic minority groups, following complaints that a more accurate version generated a reduced number of investigative leads.

The Technology in Practice

British police use the police national database (PND) to carry out searches using historical face recognition. This process involves comparing a reference photograph of a suspect against a database of more than 19 million mugshots to find possible hits.

Acknowledged Discrimination

The UK interior ministry conceded last week that the system was biased. This admission came after a study by the National Physical Laboratory (NPL) found it misidentified people of Black and Asian heritage and females at much greater frequency than Caucasian males. The ministry stated it “took steps on the findings”.

“It prompts the question of whether facial recognition only becomes effective if users tolerate discrimination in ethnicity and sex. Convenience is a weak argument for overriding basic freedoms.”

Known Issue

Official papers reveal that this bias has been known about for more than a year. Furthermore, police forces lobbied to reverse an earlier ruling that was designed to address the problem.

Senior officers were notified of the system's bias in late 2024. The Home Office-commissioned laboratory study found the system was more likely to produce false positives for images depicting females, individuals of Black ethnicity, and those aged 40 and under.

A Policy U-Turn

In response, the National Police Chiefs’ Council (NPCC) mandated that the accuracy setting required for potential matches be raised to a point where the bias was significantly reduced.

However, this directive was overturned the following month after forces complained that the adjusted system was producing a lower number of “investigative leads”. Internal records indicate the higher threshold reduced the proportion of queries that yielded possible identifications from over half to a mere 14%.

Severe Disparities

Although the authorities refused to say what threshold is now in operation, the latest independent review found the system could generate false positives for women of Black heritage nearly a hundred times more frequently than for Caucasian women at specific configurations.

The Home Office stated on these results: “Our evaluation identified that in a limited set of circumstances the algorithm is has a greater tendency 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 confidence threshold, the NPCC documents note: “The change greatly lessens the effect of bias across protected characteristics of ethnicity, 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 opened a ten-week public review on its plans to widen the use of facial recognition technology. Policing minister the relevant minister has labeled the technology as the “biggest breakthrough since DNA matching”.

Expert and Oversight Concerns

Abimbola Johnson, head of the advisory panel for the national policing equality strategy, commented: “We observed very little discussion through race action plan meetings of the technology deployment even with obvious cross-over with the strategy's goals.

“These revelations show yet again that the pledges to combat discrimination the police has made via the equality initiative are not being translated into wider practice. Independent assessments have cautioned that new technologies are being implemented in a context where ethnic inequalities, inadequate oversight and poor data collection continue to exist.

“All deployment of this technology must meet rigorous official guidelines, be subject to external review, and demonstrate it reduces 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 new algorithm has been externally evaluated and procured, which has demonstrated no measurable discrimination. It will be trialled in the coming months and will be undergo evaluation.

“Our priority is ensuring public safety. This gamechanging technology will assist officers to apprehend and prosecute offenders. There is human involvement in each stage of the procedure and no arrest or charge would be taken without trained officers carefully reviewing the output.”