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Law enforcement agencies across the UK effectively campaigned to use a face scanning system acknowledged as discriminatory against females, young people, and members of minority ethnic backgrounds, after complaining that a more accurate version produced fewer potential suspects.

How the System Works

British police utilize the national police database to conduct searches using historical face recognition. This procedure involves comparing a “probe image” of a person of interest against a database of more than 19 million mugshots to identify potential matches.

Admitted Bias

The Home Office conceded last week that the system was biased. This admission came after a review by the National Physical Laboratory (NPL) found it misidentified Black and Asian people and females at significantly higher rates than Caucasian males. The Home Office said it “had acted on the findings”.

“This raises the question of whether facial recognition only becomes effective if users tolerate discrimination in ethnicity and sex. Convenience is a poor argument for disregarding basic freedoms.”

Long-Standing Problem

Internal documents show that this discriminatory flaw has been known about for over twelve months. Furthermore, law enforcement argued to overturn an earlier ruling that was intended to address the problem.

Senior officers were informed of the system's bias in late 2024. The Home Office-commissioned laboratory study found the system was had a higher probability to produce false positives for photos of women, Black people, and those under 40 years old.

A Policy U-Turn

In reaction, the national police leadership body ordered that the accuracy setting required for possible hits be raised to a point where the bias was greatly diminished.

However, this directive was overturned the following month following complaints from police that the adjusted system was producing fewer “investigative leads”. Internal records indicate the higher threshold reduced the proportion of queries resulting in possible identifications from over half to a mere 14%.

Severe Disparities

Although the Home Office and NPCC declined to specify what setting is now in operation, the latest NPL study discovered the system could generate incorrect matches for women of Black heritage nearly a hundred times more frequently than for Caucasian women at specific configurations.

The ministry stated on these findings: “The testing found that in a specific scenarios the software is has a greater tendency to wrongly flag some population segments in its search results.”

Operational Effectiveness vs. Bias

Outlining the effect of the brief increase to the system's accuracy setting, the NPCC documents state: “The change greatly lessens 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 forces complained that “a previously useful tool now delivered results of limited benefit”.

Wider Implementation Proposals

Meanwhile, the government has launched a ten-week consultation on its plans to expand the use of biometric scanning systems. Policing minister the relevant minister has described the tool as the “most significant advance since DNA matching”.

Criticism from Advisors and Monitors

Abimbola Johnson, chair of the advisory panel for the national policing equality strategy, said: “We observed very little discussion in race action plan meetings of the technology deployment even with obvious cross-over with the plan’s concerns.

“These revelations show once again that the anti-racism commitments the police has made through the race action plan are not being translated into broader operations. Our reports have warned that innovative tools are being rolled out in a context where racial disparities, inadequate oversight and poor data collection continue to exist.

“Any use of facial recognition must adhere to rigorous official guidelines, be independently scrutinised, and prove it reduces rather than exacerbates racial disparity.”

Home Office Response

A Home Office spokesperson said: “The Home Office treat the conclusions of the study with utmost gravity and we have implemented changes. 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 protecting the public. This gamechanging technology will support police to put criminals and rapists behind bars. There is officer review in every step of the procedure and no arrest or charge would be taken without trained officers meticulously examining the results.”