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Law enforcement agencies across the United Kingdom successfully lobbied to use a face scanning system known to be discriminatory against women, young people, and individuals from minority ethnic backgrounds, following complaints that a more accurate version produced a reduced number of investigative leads.

The Technology in Practice

British police utilize the police national database (PND) to conduct searches using historical face recognition. This process entails matching a “probe image” of a suspect against a repository of over 19 million mugshots to identify possible hits.

Admitted Bias

The Home Office conceded last week that the system was biased. This admission came after a study by the National Physical Laboratory (NPL) determined it misidentified Black and Asian people and females at significantly higher rates than Caucasian males. 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 race and sex. Convenience is a poor argument for overriding basic freedoms.”

Known Issue

Internal documents reveal that this bias has been known about for more than a year. Furthermore, police forces lobbied to reverse an earlier ruling that was intended to address the problem.

Police bosses were informed of the system's bias in late 2024. The Home Office-commissioned laboratory study found the system was more likely to suggest false positives for images depicting females, individuals of Black ethnicity, and those aged 40 and under.

A Policy U-Turn

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

However, this decision was reversed the next month after forces complained that the adjusted system was producing fewer “useful lines of inquiry”. NPCC documents show the stricter setting cut the proportion of queries resulting in potential matches from 56% to a just 14%.

Profound Inequalities

Although the authorities refused to say what threshold is currently used, the recent independent review discovered the system could generate incorrect matches for women of Black heritage almost 100 times more often than for Caucasian women at specific configurations.

The Home Office stated on these results: “The testing identified that in a limited set of circumstances the software is has a greater tendency 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 NPCC documents note: “This adjustment greatly lessens the impact of bias across legally safeguarded attributes of ethnicity, age and gender but had a substantially detrimental effect on police efficiency”. The papers further note that forces complained 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 consultation on its plans to widen the use of facial recognition technology. Policing minister Sarah Jones has labeled the technology as the “most significant advance since DNA matching”.

Criticism from Advisors and Monitors

The chair of a police oversight board, chair of the advisory panel for the national policing equality strategy, commented: “We observed very little consideration through equality strategy sessions of the technology deployment despite clear relevance with the plan’s concerns.

“This disclosure show yet again that the pledges to combat discrimination the police has made via the equality initiative are failing to be integrated into broader operations. Our reports have cautioned that innovative tools are being implemented in a context where racial disparities, inadequate oversight and faulty information gathering continue to exist.

“All deployment of this technology must adhere to strict national standards, be subject to external review, and prove it reduces rather than compounds racial disparity.”

Official Statement

A government representative said: “The Home Office treat the findings of the study with utmost gravity and we have already taken action. A new algorithm has been externally evaluated and procured, which has demonstrated no measurable discrimination. It will be trialled early next year and will be undergo evaluation.

“Our priority is protecting the public. This gamechanging technology will assist police to apprehend and prosecute offenders. There is human involvement in each stage of the procedure and no arrest or charge would be pursued without trained officers carefully reviewing the results.”