🔗 Share this article

Police forces across the UK effectively campaigned to deploy a face scanning system known to be biased against women, youths, and members of minority ethnic backgrounds, after complaining that a less biased version produced fewer investigative leads.

The Technology in Practice

British police use the police national database (PND) to carry out retrospective facial recognition searches. This procedure entails comparing a “probe image” of a suspect against a repository of more than 19 million custody photos to find possible hits.

Acknowledged Discrimination

The Home Office admitted last week that the technology was flawed. This admission came after a study by the National Physical Laboratory (NPL) found it incorrectly matched Black and Asian people and women at significantly higher rates than white men. The ministry said it “took steps on the findings”.

“This raises the issue of whether facial recognition only becomes effective if users accept discrimination in race and gender. Convenience is a weak argument for disregarding fundamental rights.”

Known Issue

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

Senior officers were informed of the system's bias in September 2024. The Home Office-commissioned NPL review concluded the system was more likely to produce incorrect matches for photos of females, individuals of Black ethnicity, and those under 40 years old.

A Reversed Decision

In response, the National Police Chiefs’ Council (NPCC) ordered that the accuracy setting required for potential matches be raised to a point where the disparity was greatly diminished.

However, this directive was reversed the next month after forces complained that the modified technology was producing fewer “investigative leads”. Internal records show the higher threshold reduced the proportion of searches that yielded possible identifications from over half to a just under 15%.

Profound Inequalities

Although the Home Office and NPCC declined to specify what setting is currently used, the recent NPL study discovered the system could produce false positives for women of Black heritage nearly a hundred times more frequently than for Caucasian women at specific configurations.

The ministry commented on these results: “The testing found 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

Describing the impact of the temporary raise to the system's accuracy setting, the police records note: “This adjustment greatly lessens the impact of discrimination across legally safeguarded attributes of race, generation and gender but had a significant negative impact on operational effectiveness”. The documents further note that police units argued that “a previously useful tool 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 Sarah Jones has described the technology as the “biggest breakthrough since DNA matching”.

Expert and Oversight Concerns

The chair of a police oversight board, chair of the independent scrutiny and oversight board for the police race action plan, said: “We observed very little consideration in race action plan meetings of the facial recognition rollout despite obvious cross-over with the strategy's goals.

“These revelations demonstrate yet again that the anti-racism commitments policing has undertaken via the equality initiative are failing to be integrated into broader operations. Independent assessments have cautioned that new technologies are being implemented in a landscape where ethnic inequalities, weak scrutiny and poor data collection already persist.

“Any use of facial recognition must meet strict national standards, be independently scrutinised, and prove it reduces rather than exacerbates racial disparity.”

Official Statement

A Home Office spokesperson said: “We takes the findings of the study seriously and we have implemented changes. A new algorithm has been externally evaluated and acquired, 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 revolutionary tool will support police to apprehend and prosecute offenders. There is officer review in each stage of the process and no further action would be pursued without trained officers carefully reviewing the output.”