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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, youths, and members of minority ethnic backgrounds, after complaining that a more accurate version produced a reduced number of potential suspects.

How the System Works

UK forces use the national police database to carry out searches using historical face recognition. This procedure involves matching a “probe image” of a person of interest 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 came after a study by the National Physical Laboratory (NPL) determined it incorrectly matched Black and Asian people and women at much greater frequency than Caucasian males. The Home Office said it “had acted on the findings”.

“It prompts the question of whether this technology only becomes useful if users tolerate discrimination in ethnicity and gender. Convenience is a poor argument for overriding basic freedoms.”

Known Issue

Internal documents show that this bias has been known about for more than a year. Furthermore, police forces lobbied to reverse an initial decision that was designed to address the problem.

Senior officers were informed of the system's bias in late 2024. The Home Office-commissioned NPL review concluded the system was more likely to produce false positives for images depicting females, individuals of Black ethnicity, and those aged 40 and under.

A Reversed Decision

In reaction, the National Police Chiefs’ Council (NPCC) mandated that the confidence threshold required for potential matches be raised to a point where the disparity was significantly reduced.

However, this decision was overturned the following month after forces complained that the modified technology was generating fewer “investigative leads”. NPCC documents indicate the stricter setting cut the number of searches that yielded potential matches from 56% to a mere under 15%.

Severe Disparities

Although the authorities declined to specify what threshold is currently used, the latest NPL study found the system could produce incorrect matches for women of Black heritage almost 100 times more frequently than for white women at specific configurations.

The ministry commented on these results: “Our evaluation identified that in a specific scenarios the algorithm is has a greater tendency to wrongly flag some population segments in its match reports.”

Operational Effectiveness vs. Bias

Outlining the effect of the temporary raise to the system's confidence threshold, the NPCC documents state: “The change significantly reduces the effect of bias across legally safeguarded attributes of ethnicity, generation and sex but had a substantially detrimental effect on operational effectiveness”. The documents further note that police units argued that “a previously useful tool now delivered results of questionable value”.

Broader Rollout Plans

Meanwhile, the UK administration has launched a ten-week public review on its plans to widen the use of facial recognition technology. 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 police race action plan, commented: “We observed very little consideration in race action plan meetings of the facial recognition rollout despite clear relevance with the strategy's goals.

“These revelations demonstrate yet again that the pledges to combat discrimination the police has made via the race action plan are failing to be integrated into broader operations. Independent assessments have cautioned that innovative tools are being implemented in a context where ethnic inequalities, weak scrutiny and faulty information gathering continue to exist.

“All deployment of this technology must meet rigorous official guidelines, be independently scrutinised, and demonstrate it reduces rather than exacerbates ethnic bias.”

Official Statement

A government representative said: “We treat the findings of the study with utmost gravity and we have implemented changes. A updated software has been independently tested and acquired, which has no statistically significant bias. It will be tested early next year and will be undergo evaluation.

“The foremost aim is protecting the public. This gamechanging technology will support officers to apprehend and prosecute offenders. There is officer review in every step of the procedure and no further action would be taken without specialist personnel carefully reviewing the results.”