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Police forces across the UK successfully lobbied to use a facial recognition system acknowledged as 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.

How the System Works

UK forces use the police national database (PND) to carry out retrospective facial recognition searches. This process involves comparing a reference photograph of a suspect against a database of more than 19 million custody photos to find potential matches.

Admitted Bias

The Home Office admitted last week that the system 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 women at significantly higher rates than Caucasian males. The ministry stated it “had acted on the findings”.

“This raises the question of whether facial recognition only becomes useful if users tolerate biases in ethnicity and gender. Convenience is a weak argument for overriding fundamental rights.”

Known Issue

Official papers show that this discriminatory flaw has been known about for over twelve months. Furthermore, police forces argued to overturn an initial decision that was designed to mitigate the problem.

Police bosses were notified of the algorithmic discrimination in September 2024. The government-ordered laboratory study found the system was more likely to produce incorrect matches for images depicting women, Black people, and those under 40 years old.

A Policy U-Turn

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

However, this decision was reversed the following month after forces complained that the adjusted system was generating a lower number of “investigative leads”. NPCC documents indicate the higher threshold reduced the proportion of searches that yielded potential matches from over half to a just under 15%.

Severe Disparities

Although the authorities refused to say what threshold is now in operation, the latest independent review discovered the system could produce incorrect matches for Black women nearly a hundred times more frequently than for white women at specific configurations.

The Home Office commented on these results: “The testing identified that in a limited set of circumstances the algorithm is more likely to wrongly flag some demographic groups in its search results.”

Balancing Utility and Fairness

Outlining the effect of the brief increase to the system's accuracy setting, the NPCC documents note: “The change greatly lessens the impact of discrimination across legally safeguarded attributes of race, generation and sex but had a significant negative impact on police efficiency”. The papers further note that police units complained that “a once effective tactic now delivered results of questionable value”.

Broader Rollout Plans

Meanwhile, the government has launched a ten-week public review on its proposals to widen the use of facial recognition technology. Policing minister the relevant minister has labeled the technology as the “biggest breakthrough since DNA matching”.

Expert and Oversight Concerns

Abimbola Johnson, chair of the advisory panel for the national policing equality strategy, commented: “There was very little consideration in equality strategy sessions of the technology deployment even with obvious cross-over with the plan’s concerns.

“This disclosure show once again that the anti-racism commitments the police has undertaken through the equality initiative are not being translated into broader operations. Our reports have warned that new technologies are being rolled out in a landscape where racial disparities, weak scrutiny and poor data collection continue to exist.

“Any use of facial recognition must adhere to strict national standards, be subject to external review, and prove it reduces rather than exacerbates racial disparity.”

Home Office Response

A Home Office spokesperson said: “We takes the findings of the study seriously and we have already taken action. A updated software has been independently tested and procured, which has demonstrated no measurable discrimination. It will be trialled in the coming months and will be subject to evaluation.

“Our priority is ensuring public safety. This revolutionary tool will assist officers to apprehend and prosecute offenders. There is officer review in every step of the process and no arrest or charge would be pursued without specialist personnel meticulously examining the results.”