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Police forces across the United Kingdom effectively campaigned to deploy a face scanning system known to be discriminatory against females, youths, and members of minority ethnic backgrounds, following complaints that a more accurate version generated a reduced number of potential suspects.

The Technology in Practice

British police utilize the police national database (PND) to carry out searches using historical face recognition. This process entails comparing a “probe image” of a person of interest against a database of over 19 million mugshots to find possible hits.

Admitted Bias

The Home Office conceded last week that the system was biased. This acknowledgment came after a review by the National Physical Laboratory (NPL) found it incorrectly matched Black and Asian people and females at significantly higher rates than Caucasian males. The ministry stated it “took steps on the findings”.

“It prompts the question of whether this technology only becomes effective if users tolerate biases in ethnicity and sex. Convenience is a poor argument for disregarding fundamental rights.”

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 designed to mitigate the problem.

Senior officers were informed of the algorithmic discrimination in late 2024. The Home Office-commissioned laboratory study found the system was had a higher probability to suggest false positives for photos of women, Black people, and those aged 40 and under.

A Reversed Decision

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

However, this directive was overturned the next month after forces complained that the modified technology was generating a lower number of “investigative leads”. NPCC documents show the higher threshold cut the number of queries resulting in possible identifications from over half to a mere under 15%.

Profound Inequalities

Although the authorities declined to specify what threshold is now in operation, the recent independent review discovered the system could produce false positives for women of Black heritage nearly a hundred times more frequently than for Caucasian women at specific configurations.

The ministry commented on these results: “Our evaluation found that in a limited set of circumstances the algorithm is has a greater tendency to wrongly flag some demographic groups in its match reports.”

Balancing Utility and Fairness

Describing the impact of the temporary raise to the system's accuracy setting, the NPCC documents state: “This adjustment significantly reduces the impact of bias across protected characteristics of race, age and sex but had a significant negative impact on police efficiency”. The papers add that police units complained that “a previously useful tool returned outcomes of questionable value”.

Broader Rollout Plans

Meanwhile, the UK administration has launched a ten-week consultation on its plans to widen the use of facial recognition technology. Policing minister the relevant minister has described the tool 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: “There was scant discussion in equality strategy sessions of the technology deployment despite clear relevance with the strategy's goals.

“This disclosure show yet again that the anti-racism commitments the police has undertaken via the race action plan are not being translated into wider practice. Our reports have cautioned that new technologies are being implemented in a landscape where racial disparities, weak scrutiny and poor data collection already persist.

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

Official Statement

A government representative stated: “The Home Office treat the findings of the study seriously and we have implemented changes. A new algorithm has been externally evaluated and procured, which has no statistically significant bias. It will be tested in the coming months and will be undergo further assessment.

“Our priority is ensuring public safety. This revolutionary tool will assist police to put criminals and rapists behind bars. There is human involvement in each stage of the process and no further action would be taken without specialist personnel carefully reviewing the output.”