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Police forces across the United Kingdom effectively campaigned to deploy a face scanning system known to be discriminatory against females, youths, and individuals from ethnic minority groups, following complaints that a less biased version produced fewer potential suspects.

How the System Works

UK forces use the police national database (PND) to carry out retrospective facial recognition searches. This procedure entails matching a “probe image” of a suspect against a database of more than 19 million custody photos to find possible hits.

Admitted Bias

The UK interior ministry conceded last week that the system was flawed. This admission came after a study by the government's National Physical Laboratory determined it incorrectly matched people of Black and Asian heritage and females at much greater frequency than Caucasian males. The ministry stated it “took steps on the findings”.

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

Known Issue

Official papers show that this bias has been known about for more than a year. Furthermore, law enforcement argued to overturn an initial decision that was intended to mitigate the problem.

Senior officers were notified of the system's bias in September 2024. The government-ordered laboratory study found the system was had a higher probability to produce incorrect matches for images depicting females, individuals of Black ethnicity, and those aged 40 and under.

A Policy U-Turn

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

However, this directive was overturned the following month following complaints from police that the modified technology was producing a lower number of “useful lines of inquiry”. Internal records show the higher threshold reduced the number of queries that yielded possible identifications from over half to a just 14%.

Severe Disparities

Although the authorities refused to say what setting is now in operation, the recent NPL study discovered the system could generate false positives for Black women nearly a hundred times more often than for white women at specific configurations.

The Home Office 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 match reports.”

Operational Effectiveness vs. Bias

Outlining the impact of the temporary raise to the system's confidence threshold, the police records note: “The change significantly reduces the impact of discrimination across protected characteristics of ethnicity, age and sex but had a significant negative impact on police efficiency”. The papers add that forces complained that “a previously useful tool now delivered outcomes of limited benefit”.

Broader Rollout Plans

Meanwhile, the UK administration has opened a ten-week public review on its proposals to widen the use of biometric scanning systems. Policing minister the relevant minister has described the technology as the “most significant advance since DNA matching”.

Expert and Oversight Concerns

Abimbola Johnson, head of the independent scrutiny and oversight board for the national policing equality strategy, commented: “There was scant consideration through equality strategy sessions of the facial recognition rollout even with obvious cross-over with the plan’s concerns.

“This disclosure show yet again that the anti-racism commitments policing has made via the equality initiative are not being translated into wider practice. Independent assessments have warned that innovative tools are being rolled out in a landscape where ethnic inequalities, weak scrutiny and poor data collection continue to exist.

“All deployment of this technology must meet rigorous official guidelines, be independently scrutinised, and demonstrate it diminishes rather than compounds ethnic bias.”

Home Office Response

A Home Office spokesperson said: “We takes the conclusions of the study seriously and we have implemented changes. A new algorithm has been externally evaluated and procured, which has demonstrated no measurable discrimination. It will be trialled early next year and will be subject to evaluation.

“The foremost aim is ensuring public safety. This revolutionary tool will assist police to put criminals and rapists behind bars. There is officer review in each stage of the procedure and no arrest or charge would be pursued without trained officers meticulously examining the output.”