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Law enforcement agencies across the United Kingdom effectively campaigned to use a face scanning system known to be discriminatory against females, youths, and members of minority ethnic backgrounds, following complaints that a less biased version produced fewer investigative leads.

The Technology in Practice

UK forces utilize the national police database to conduct searches using historical face recognition. This process involves comparing a reference photograph of a person of interest against a repository of over 19 million custody photos to find possible hits.

Admitted Bias

The UK interior ministry conceded last week that the technology was biased. This admission came after a review by the National Physical Laboratory (NPL) determined it incorrectly matched Black and Asian people and women at significantly higher rates than white men. The Home Office stated it “had acted on the findings”.

“This raises the issue of whether facial recognition only becomes useful if users tolerate biases in ethnicity and gender. Convenience is a poor argument for disregarding basic freedoms.”

Known Issue

Internal documents show 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 mitigate the problem.

Police bosses were notified of the algorithmic discrimination in late 2024. The Home Office-commissioned NPL review found the system was had a higher probability to suggest false positives for photos of females, Black people, and those under 40 years old.

A Policy U-Turn

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

However, this decision was reversed the following month following complaints from police that the modified technology was producing fewer “investigative leads”. Internal records show the stricter setting cut the proportion of searches that yielded possible identifications from 56% to a just under 15%.

Severe Disparities

Although the Home Office and NPCC refused to say what threshold is now in operation, the latest NPL study discovered the system could produce incorrect matches for Black women nearly a hundred times more frequently than for Caucasian women at specific configurations.

The Home Office stated on these results: “The testing found that in a limited set of circumstances the algorithm is more likely to incorrectly include some demographic groups in its search results.”

Balancing Utility and Fairness

Outlining the effect of the temporary raise to the system's accuracy setting, the NPCC documents state: “This adjustment significantly reduces the impact of discrimination across protected characteristics of ethnicity, age and gender but had a significant negative impact on police efficiency”. The documents further note that forces complained that “a once effective tactic returned outcomes of limited benefit”.

Wider Implementation Proposals

Meanwhile, the government has opened a ten-week public review on its proposals to expand the use of biometric scanning systems. The minister for police Sarah Jones has labeled the tool as the “biggest breakthrough since DNA matching”.

Expert and Oversight Concerns

The chair of a police oversight board, chair of the advisory panel for the police race action plan, commented: “There was very little consideration through race action plan meetings 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 undertaken via the race action plan are not being translated into broader operations. Independent assessments have warned that innovative tools are being rolled out in a landscape where ethnic inequalities, weak scrutiny and faulty information gathering 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 ethnic bias.”

Official Statement

A government representative stated: “The Home Office treat the findings of the study seriously 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.

“Our priority is ensuring public safety. This gamechanging technology will assist officers to apprehend and prosecute offenders. There is human involvement in every step of the procedure and no further action would be pursued without trained officers carefully reviewing the output.”