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Law enforcement agencies across the UK successfully lobbied to deploy a face scanning system known to be biased against females, young people, and members of minority ethnic backgrounds, after complaining that a more accurate version generated fewer potential suspects.

The Technology in Practice

UK forces use the police national database (PND) to carry out retrospective facial recognition searches. This process involves comparing a “probe image” of a person of interest against a repository of over 19 million custody photos to find potential matches.

Admitted Bias

The UK interior ministry conceded last week that the system was flawed. This acknowledgment followed a review by the government's National Physical Laboratory determined it incorrectly matched Black and Asian people and females at much greater frequency than white men. The ministry said it “took steps on the findings”.

“It prompts the question of whether facial recognition only becomes effective if users tolerate biases in race and gender. Convenience is a weak argument for overriding fundamental rights.”

Known Issue

Official papers reveal that this discriminatory flaw has been recognized for over twelve months. Furthermore, police forces lobbied to reverse an initial decision that was designed to mitigate the problem.

Senior officers 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 images depicting females, Black people, and those under 40 years old.

A Policy U-Turn

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

However, this directive was overturned the next month after forces complained that the adjusted system was generating a lower number of “investigative leads”. Internal records indicate the higher threshold reduced the proportion of searches resulting in potential matches from 56% to a just under 15%.

Profound Inequalities

Although the Home Office and NPCC refused to say what setting is now in operation, the latest NPL study found the system could produce false positives for women of Black heritage nearly a hundred times more frequently than for white women at specific configurations.

The ministry commented on these findings: “The testing found that in a specific scenarios the algorithm is has a greater tendency to wrongly flag some population segments in its search results.”

Operational Effectiveness vs. Bias

Outlining the impact of the brief increase to the system's accuracy setting, the NPCC documents state: “The change significantly reduces the impact of discrimination across legally safeguarded attributes of race, age and gender but had a significant negative impact on police efficiency”. The papers further note that police units argued that “a once effective tactic returned results of limited benefit”.

Broader Rollout Plans

Meanwhile, the government has launched a two-and-a-half-month public review on its proposals to expand the use of facial recognition technology. Policing minister the relevant minister has described the technology as the “most significant advance since DNA matching”.

Expert and Oversight Concerns

The chair of a police oversight board, head of the independent scrutiny and oversight board 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 strategy's goals.

“This disclosure demonstrate once again that the anti-racism commitments policing has undertaken through the equality initiative are not being translated into broader operations. Our reports have warned that innovative tools are being rolled out in a landscape where ethnic inequalities, inadequate oversight and faulty information gathering already persist.

“Any use of facial recognition must adhere to strict national standards, be independently scrutinised, and prove it diminishes rather than compounds racial disparity.”

Official Statement

A government representative said: “The Home Office takes the findings of the study with utmost gravity and we have implemented changes. A new algorithm has been externally evaluated and procured, which has no statistically significant bias. It will be trialled early next year and will be subject to further assessment.

“The foremost aim is protecting the public. This revolutionary tool will support officers to apprehend and prosecute offenders. There is officer review in each stage of the process and no arrest or charge would be taken without trained officers meticulously examining the results.”