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Police forces across the UK successfully lobbied to deploy a facial recognition system known to be biased against females, young people, and members of minority ethnic backgrounds, following complaints that a less biased version generated fewer potential suspects.

How the System Works

UK forces utilize the police national database (PND) to carry out searches using historical face recognition. This process involves matching a “probe image” of a suspect against a repository of more than 19 million custody photos to identify possible hits.

Admitted Bias

The UK interior ministry conceded last week that the technology was biased. This admission followed a study 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 ministry said it “had acted on the findings”.

“It prompts the issue of whether facial recognition only becomes effective if users tolerate discrimination in ethnicity and sex. Convenience is a poor argument for overriding fundamental rights.”

Known Issue

Internal documents show that this discriminatory flaw has been recognized for over twelve months. Furthermore, law enforcement argued to overturn an earlier ruling that was designed to address the problem.

Senior officers were informed of the algorithmic discrimination in late 2024. The Home Office-commissioned laboratory study concluded the system was more likely to suggest false positives 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 potential matches be increased to a level where the disparity was significantly reduced.

However, this directive was reversed the following month following complaints from police that the modified technology was producing a lower number of “investigative leads”. NPCC documents show the stricter setting cut the number of queries that yielded potential matches from 56% to a mere under 15%.

Profound Inequalities

Although the authorities declined to specify what threshold is currently used, the recent NPL study discovered the system could generate incorrect matches for women of Black heritage nearly a hundred times more often than for white women at certain settings.

The Home Office commented on these results: “The testing identified that in a limited set of circumstances the software is has a greater tendency to wrongly flag some population segments in its search results.”

Operational Effectiveness vs. Bias

Outlining the impact of the temporary raise to the system's confidence threshold, the police records state: “The change greatly lessens the impact of bias across legally safeguarded attributes of race, generation and gender but had a substantially detrimental effect on police efficiency”. The papers add that police units complained that “a once effective tactic returned results of limited benefit”.

Broader Rollout Plans

Meanwhile, the government has opened a two-and-a-half-month consultation on its plans to expand the use of biometric scanning systems. The minister for police Sarah Jones has described the technology as the “biggest breakthrough since DNA matching”.

Criticism from Advisors and Monitors

The chair of a police oversight board, head of the independent scrutiny and oversight board for the national policing equality strategy, said: “We observed very little consideration in equality strategy sessions of the facial recognition rollout despite clear relevance with the strategy's goals.

“This disclosure show yet again that the pledges to combat discrimination policing has made via the race action plan are not being translated into wider practice. Our reports have warned that new technologies are being implemented in a context where racial disparities, weak scrutiny and faulty information gathering already persist.

“Any use of this technology must adhere to strict national standards, be independently scrutinised, and prove it diminishes rather than compounds ethnic bias.”

Official Statement

A government representative stated: “We takes the findings of the report with utmost gravity and we have already taken action. 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 undergo evaluation.

“The foremost aim is ensuring public safety. This revolutionary tool will support officers to apprehend and prosecute offenders. There is human involvement in each stage of the procedure and no further action would be pursued without trained officers meticulously examining the results.”