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Police forces across the UK successfully lobbied to deploy a facial recognition system known to be discriminatory against females, youths, and individuals from ethnic minority groups, after complaining that a less biased version generated a reduced number of investigative leads.

The Technology in Practice

UK forces utilize the police national database (PND) to carry out searches using historical face recognition. This process involves comparing a reference photograph of a suspect against a database of over 19 million custody photos to find potential matches.

Acknowledged Discrimination

The UK interior ministry conceded last week that the system was biased. This acknowledgment followed a review by the National Physical Laboratory (NPL) found it misidentified Black and Asian people and women at much greater frequency than white men. The ministry said it “took steps on the findings”.

“This raises the question of whether this technology only becomes effective if users tolerate biases in race and sex. Operational ease is a poor argument for overriding fundamental rights.”

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 designed to mitigate 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 incorrect matches for images depicting females, Black people, and those aged 40 and under.

A Reversed Decision

In response, the national police leadership body ordered that the confidence threshold required for potential matches be raised to a point where the bias was significantly reduced.

However, this decision was reversed the next month following complaints from police that the adjusted system was producing a lower number of “investigative leads”. Internal records indicate the higher threshold reduced the proportion of searches resulting in possible identifications from over half to a mere under 15%.

Profound Inequalities

Although the Home Office and NPCC refused to say what threshold is currently used, the latest NPL study discovered the system could generate incorrect matches for women of Black heritage nearly a hundred times more frequently than for white women at specific configurations.

The Home Office commented on these results: “The testing found that in a specific scenarios the algorithm is more likely to incorrectly include some demographic groups in its match reports.”

Operational Effectiveness vs. Bias

Describing the effect of the brief increase to the system's confidence threshold, the police records note: “The change greatly lessens the impact of bias across legally safeguarded attributes of ethnicity, generation and gender but had a substantially detrimental effect on police efficiency”. The documents further note that forces argued that “a once effective tactic now delivered outcomes of limited benefit”.

Broader Rollout Plans

Meanwhile, the UK administration has opened a ten-week public review on its plans to expand the use of biometric scanning systems. Policing minister 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 advisory panel for the national policing equality strategy, commented: “We observed scant consideration through race action plan meetings of the technology deployment despite clear relevance with the plan’s concerns.

“These revelations demonstrate once again that the pledges to combat discrimination policing has made through the race action plan are not being translated into broader operations. Independent assessments have warned that new technologies are being implemented in a context where ethnic inequalities, weak scrutiny and faulty information gathering continue to exist.

“Any use of facial recognition must adhere to rigorous official guidelines, be independently scrutinised, and prove it reduces rather than exacerbates ethnic bias.”

Official Statement

A Home Office spokesperson said: “The Home Office takes the conclusions of the report with utmost gravity and we have already taken action. A new algorithm has been independently tested and procured, which has no statistically significant bias. It will be trialled in the coming months and will be undergo further assessment.

“The foremost aim is ensuring public safety. This gamechanging technology will assist officers to put criminals and rapists behind bars. There is officer review in every step of the procedure and no further action would be taken without specialist personnel carefully reviewing the output.”