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Law enforcement agencies across the UK successfully lobbied to use a face scanning system known to be biased against females, young people, and individuals from ethnic minority groups, after complaining that a more accurate version generated a reduced number of investigative leads.

The Technology in Practice

UK forces use the national police database to carry out retrospective facial recognition searches. This procedure entails comparing a reference photograph of a suspect against a database of over 19 million mugshots to find potential matches.

Admitted Bias

The UK interior ministry admitted last week that the technology was flawed. This admission followed a review by the National Physical Laboratory (NPL) found it misidentified Black and Asian people and women at significantly higher rates than Caucasian males. The ministry said it “took steps on the findings”.

“This raises the issue of whether this technology only becomes useful if users tolerate biases in ethnicity and sex. Convenience is a weak argument for disregarding fundamental rights.”

Known Issue

Official papers reveal that this discriminatory flaw has been known about for more than a year. Furthermore, law enforcement lobbied to reverse an earlier ruling that was intended to mitigate the problem.

Police bosses were notified of the system's bias in late 2024. The government-ordered NPL review found the system was had a higher probability to suggest incorrect matches for photos of women, individuals of Black ethnicity, and those under 40 years old.

A Policy U-Turn

In response, the national police leadership body mandated that the confidence threshold required for possible hits be increased to a level where the disparity was greatly diminished.

However, this decision was reversed the following month after forces complained that the modified technology was producing a lower number of “investigative leads”. NPCC documents indicate the stricter setting cut the number of queries resulting in potential matches from over half to a mere under 15%.

Profound Inequalities

Although the Home Office and NPCC declined to specify what threshold is now in operation, the latest NPL study discovered the system could produce false positives for Black women nearly a hundred times more frequently than for white women at specific configurations.

The ministry stated on these results: “The testing identified that in a limited set of circumstances the algorithm is more likely to wrongly flag some population segments in its search results.”

Balancing Utility and Fairness

Outlining the effect of the temporary raise to the system's accuracy setting, the police records note: “The change significantly reduces the impact of bias across protected characteristics of race, age and gender but had a substantially detrimental effect on police efficiency”. The documents further note that police units argued that “a previously useful tool returned outcomes of questionable value”.

Wider Implementation Proposals

Meanwhile, the UK administration has opened a two-and-a-half-month consultation on its plans to widen the use of facial recognition technology. The minister for police the relevant minister has labeled the technology as the “most significant advance since genetic fingerprinting”.

Criticism from Advisors and Monitors

Abimbola Johnson, head of the advisory panel for the national policing equality strategy, commented: “We observed very little discussion through equality strategy sessions of the facial recognition rollout even with obvious cross-over with the plan’s concerns.

“This disclosure show once again that the pledges to combat discrimination the police has undertaken through the equality initiative are not being translated into wider practice. Our reports have cautioned that new technologies are being rolled out in a context where racial disparities, inadequate oversight and faulty information gathering already persist.

“All deployment of this technology must meet rigorous official guidelines, be subject to external review, and prove it diminishes rather than exacerbates ethnic bias.”

Home Office Response

A government representative stated: “The Home Office treat the conclusions of the study with utmost gravity and we have implemented changes. A new algorithm has been independently tested and acquired, which has no statistically significant bias. It will be trialled in the coming months and will be subject to evaluation.

“The foremost aim is ensuring public safety. 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 specialist personnel meticulously examining the results.”