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Law enforcement agencies across the UK effectively campaigned to use a facial recognition system acknowledged as biased against females, youths, and individuals from minority ethnic backgrounds, following complaints that a less biased version generated a reduced number of investigative leads.

How the System Works

British police use the police national database (PND) to conduct retrospective facial recognition searches. This process entails comparing a “probe image” of a person of interest against a database of over 19 million mugshots to find potential matches.

Admitted Bias

The UK interior ministry admitted last week that the system was flawed. This admission came after a review by the National Physical Laboratory (NPL) determined it incorrectly matched people of Black and Asian heritage and women at much greater frequency than white men. The Home Office stated it “had acted on the findings”.

“This raises the question of whether facial recognition only becomes useful if users tolerate discrimination in race and gender. Operational ease is a poor argument for disregarding basic freedoms.”

Known Issue

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

Senior officers were notified of the system's bias in September 2024. The Home Office-commissioned NPL review found the system was had a higher probability to suggest incorrect matches for images depicting females, Black people, and those under 40 years old.

A Reversed Decision

In reaction, the national police leadership body ordered that the confidence threshold required for potential matches be raised to a point where the bias was significantly reduced.

However, this decision was reversed the following month after forces complained that the modified technology was producing fewer “useful lines of inquiry”. NPCC documents show the stricter setting reduced the number of queries that yielded possible identifications from 56% to a mere under 15%.

Severe Disparities

Although the authorities refused to say what threshold is currently used, the latest independent review found the system could produce false positives for Black women nearly a hundred times more often than for white women at certain settings.

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

Balancing Utility and Fairness

Outlining the effect of the brief increase to the system's confidence threshold, the police records note: “This adjustment significantly reduces the impact of discrimination across legally safeguarded attributes of ethnicity, age and gender but had a significant negative impact on police efficiency”. The documents further note that police units complained that “a previously useful tool now delivered results of limited benefit”.

Wider Implementation Proposals

Meanwhile, the government has launched a two-and-a-half-month consultation on its proposals to widen the use of biometric scanning systems. The minister for police Sarah Jones has labeled the tool as the “biggest breakthrough since genetic fingerprinting”.

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 discussion in equality strategy sessions of the technology deployment despite obvious cross-over with the plan’s concerns.

“These revelations show yet again that the anti-racism commitments policing has made via the race action plan are not being translated into broader operations. Our reports have cautioned that new technologies are being implemented in a landscape where racial disparities, inadequate oversight and poor data collection already persist.

“All deployment of facial recognition must adhere to strict national standards, be subject to external review, and demonstrate it reduces rather than compounds ethnic bias.”

Official Statement

A government representative said: “The Home Office takes the conclusions of the study with utmost gravity and we have already taken action. A new algorithm has been externally evaluated and procured, which has demonstrated no measurable discrimination. It will be tested early next year and will be subject to further assessment.

“The foremost aim is ensuring public safety. This revolutionary tool will support police to put criminals and rapists behind bars. There is human involvement in every step of the process and no arrest or charge would be pursued without trained officers carefully reviewing the results.”