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Law enforcement agencies across the United Kingdom effectively campaigned to deploy a facial recognition system known to be biased against women, young people, and members of ethnic minority groups, after complaining that a less biased version produced a reduced number of investigative leads.

How the System Works

British police utilize the police national database (PND) to carry out searches using historical face recognition. This process entails comparing a reference photograph of a person of interest against a database of over 19 million custody photos to find potential matches.

Admitted Bias

The Home Office conceded last week that the system was flawed. This acknowledgment came after a study by the National Physical Laboratory (NPL) determined it misidentified Black and Asian people and females at significantly higher rates than white men. 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. Operational ease is a poor argument for overriding basic freedoms.”

Long-Standing Problem

Internal documents show that this discriminatory flaw has been known about for over twelve months. Furthermore, police forces lobbied to reverse an earlier ruling that was intended to address the problem.

Police bosses were notified of the algorithmic discrimination in September 2024. The Home Office-commissioned NPL review found the system was more likely to suggest false positives for images depicting women, individuals of Black ethnicity, and those under 40 years old.

A Reversed Decision

In response, the National Police Chiefs’ Council (NPCC) mandated that the accuracy setting required for possible hits be increased to a level where the disparity was greatly diminished.

However, this decision was reversed the next month following complaints from police that the modified technology was producing fewer “investigative leads”. NPCC documents show the stricter setting cut the proportion of queries resulting in potential matches from 56% to a just 14%.

Profound Inequalities

Although the Home Office and NPCC refused to say what threshold is currently used, the latest NPL study found the system could generate incorrect matches for Black women almost 100 times more often than for Caucasian women at specific configurations.

The Home Office stated on these findings: “Our evaluation found that in a limited set of circumstances the algorithm is more likely to wrongly flag some demographic groups in its search results.”

Balancing Utility and Fairness

Describing the impact of the temporary raise to the system's accuracy setting, the police records state: “The change greatly lessens the impact of discrimination across protected characteristics of race, generation and gender but had a significant negative impact on operational effectiveness”. The papers add that forces argued that “a once effective tactic now delivered outcomes of limited benefit”.

Broader Rollout Plans

Meanwhile, the government has opened a ten-week public review on its proposals to expand the use of facial recognition technology. The minister for police Sarah Jones has labeled the tool as the “biggest breakthrough since genetic fingerprinting”.

Criticism from Advisors and Monitors

The chair of a police oversight board, chair of the advisory panel for the national policing equality strategy, said: “We observed scant consideration through equality strategy sessions of the facial recognition rollout despite obvious cross-over with the plan’s concerns.

“These revelations demonstrate once again that the pledges to combat discrimination policing has undertaken via the equality initiative are not being translated into wider practice. Our reports have warned that innovative tools are being implemented in a context where racial disparities, inadequate oversight and faulty information gathering already persist.

“All deployment of this technology must meet strict national standards, be subject to external review, and prove it diminishes rather than compounds ethnic bias.”

Home Office Response

A government representative stated: “The Home Office treat the conclusions of the study seriously and we have already taken action. A new algorithm has been externally evaluated and procured, which has no statistically significant bias. It will be trialled early next year and will be subject to further assessment.

“Our priority is ensuring public safety. This revolutionary tool will assist police to apprehend and prosecute offenders. There is officer review in each stage of the procedure and no further action would be taken without trained officers meticulously examining the results.”