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Law enforcement agencies across the United Kingdom effectively campaigned to use a face scanning system known to be discriminatory against women, young people, and individuals from ethnic minority groups, following complaints that a more accurate version produced fewer investigative leads.

How the System Works

British police use the national police database to conduct retrospective facial recognition searches. This process entails comparing a reference photograph of a person of interest against a repository of over 19 million mugshots to find possible hits.

Acknowledged Discrimination

The Home Office admitted last week that the technology was flawed. This admission came after a review by the government's National Physical Laboratory determined it misidentified 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 tolerate biases in ethnicity and sex. Operational ease is a poor argument for overriding basic freedoms.”

Known Issue

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

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

A Policy U-Turn

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

However, this decision was reversed the next month after forces complained that the adjusted system was generating a lower number of “investigative leads”. Internal records indicate the higher threshold cut the number of queries resulting in potential matches from over half to a mere under 15%.

Severe Disparities

Although the authorities declined to specify what threshold is currently used, the latest independent review found the system could generate false positives for women of Black heritage nearly a hundred times more often than for white women at specific configurations.

The ministry stated on these findings: “The testing identified that in a limited set of circumstances the software is has a greater tendency to incorrectly include some demographic groups in its search results.”

Balancing Utility and Fairness

Describing the effect of the temporary raise to the system's accuracy setting, the police records note: “This adjustment greatly lessens the effect of bias across protected characteristics of ethnicity, generation and gender but had a substantially detrimental effect on police efficiency”. The papers further note that forces complained that “a once effective tactic now delivered outcomes of questionable value”.

Broader Rollout Plans

Meanwhile, the government has launched 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”.

Criticism from Advisors and Monitors

The chair of a police oversight board, head of the advisory panel for the police race action plan, commented: “We observed scant discussion through race action plan meetings of the facial recognition rollout even with obvious cross-over with the plan’s concerns.

“This disclosure demonstrate once again that the pledges to combat discrimination the police has made via the race action plan are not being translated into broader operations. Our reports have warned that innovative tools are being implemented in a context where racial disparities, weak scrutiny and poor data collection already persist.

“All deployment of this technology must meet strict national standards, be independently scrutinised, and demonstrate it reduces rather than exacerbates ethnic bias.”

Home Office Response

A Home Office spokesperson said: “The Home Office treat the conclusions of the report with utmost gravity and we have already taken action. A new algorithm has been externally evaluated and procured, which has no statistically significant bias. It will be tested early next year and will be undergo further assessment.

“The foremost aim is ensuring public safety. This gamechanging technology will assist officers to apprehend and prosecute offenders. There is human involvement in each stage of the procedure and no arrest or charge would be pursued without trained officers meticulously examining the results.”