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Police forces across the UK effectively campaigned to use a face scanning system acknowledged as biased against women, young people, and members of minority ethnic backgrounds, following complaints that a more accurate version generated a reduced number of investigative leads.

How the System Works

British police utilize the police national database (PND) to conduct retrospective facial recognition searches. This process entails comparing a “probe image” of a person of interest against a database of over 19 million custody photos to identify possible hits.

Admitted Bias

The UK interior ministry admitted last week that the technology was flawed. This admission followed a review by the government's National Physical Laboratory found it incorrectly matched people of Black and Asian heritage and females at much greater frequency than white men. The Home Office said it “had acted on the findings”.

“It prompts the question of whether this technology only becomes effective if users accept biases in ethnicity and gender. Convenience is a weak argument for disregarding basic freedoms.”

Known Issue

Internal documents show that this bias has been recognized for more than a year. Furthermore, law enforcement argued to overturn an initial decision that was designed to address 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 false positives for photos of females, individuals of Black ethnicity, and those under 40 years old.

A Reversed Decision

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

However, this decision was overturned the next month after forces complained that the modified technology was producing a lower number of “useful lines of inquiry”. NPCC documents indicate the higher threshold cut the proportion of searches resulting in possible identifications from over half to a just 14%.

Severe Disparities

Although the Home Office and NPCC refused to say what threshold is now in operation, the recent independent review found the system could produce false positives for women of Black heritage nearly a hundred times more often than for Caucasian women at certain settings.

The ministry stated on these findings: “Our evaluation found that in a specific scenarios the algorithm is has a greater tendency to wrongly flag some demographic groups in its match reports.”

Operational Effectiveness vs. Bias

Describing the impact of the temporary raise to the system's accuracy setting, the police records state: “The change greatly lessens the impact of bias across legally safeguarded attributes of ethnicity, age and gender but had a significant negative impact on police efficiency”. The documents further note that police units argued that “a once effective tactic returned results of questionable value”.

Broader Rollout Plans

Meanwhile, the UK administration has opened a two-and-a-half-month public review on its plans to widen the use of facial recognition technology. The minister for police Sarah Jones has labeled the technology as the “most significant advance since DNA matching”.

Expert and Oversight Concerns

Abimbola Johnson, chair of the independent scrutiny and oversight board for the national policing equality strategy, commented: “We observed very little discussion through race action plan meetings of the facial recognition rollout despite obvious cross-over with the plan’s concerns.

“This disclosure show yet again that the anti-racism commitments the police has made via the equality initiative are failing to be integrated into wider practice. Independent assessments have warned that innovative tools are being implemented in a context where racial disparities, weak scrutiny and faulty information gathering already persist.

“All deployment of this technology must meet strict national standards, be independently scrutinised, and prove it reduces rather than exacerbates racial disparity.”

Official Statement

A government representative stated: “We treat the conclusions of the study seriously and we have implemented changes. A updated software has been externally evaluated and acquired, which has no statistically significant bias. It will be trialled in the coming months and will be undergo further assessment.

“Our priority is protecting the public. This revolutionary tool will support officers to put criminals and rapists behind bars. There is officer review in each stage of the process and no arrest or charge would be taken without trained officers meticulously examining the output.”