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Law enforcement agencies across the UK effectively campaigned to use a face scanning system known to be biased against females, young people, and members of minority ethnic backgrounds, following complaints that a less biased version generated fewer investigative leads.

The Technology in Practice

British police utilize the national police database to conduct retrospective facial recognition searches. This procedure entails matching a reference photograph of a person of interest against a database of more than 19 million mugshots to identify potential matches.

Admitted Bias

The Home Office conceded last week that the system was biased. This acknowledgment came after a study by the National Physical Laboratory (NPL) determined it misidentified Black and Asian people and women at significantly higher rates than white men. The Home Office stated it “had acted on the findings”.

“It prompts the issue of whether this technology only becomes useful if users accept discrimination in ethnicity and gender. Convenience is a poor argument for overriding fundamental rights.”

Long-Standing Problem

Internal documents show that this discriminatory flaw has been known about for over twelve months. Furthermore, police forces argued to overturn an initial decision that was intended to mitigate the problem.

Senior officers were notified of the system's bias in late 2024. The Home Office-commissioned NPL review found the system was had a higher probability to suggest incorrect matches for images depicting women, individuals of Black ethnicity, and those aged 40 and under.

A Reversed Decision

In reaction, the National Police Chiefs’ Council (NPCC) ordered that the accuracy setting required for potential matches be raised to a point where the bias was greatly diminished.

However, this directive was overturned the following month after forces complained that the modified technology was generating fewer “investigative leads”. Internal records show the stricter setting reduced the number of queries resulting in potential matches from 56% to a just 14%.

Profound Inequalities

Although the authorities declined to specify what threshold is currently used, the recent independent review discovered the system could generate false positives for women of Black heritage almost 100 times more often than for white women at specific configurations.

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

Operational Effectiveness vs. Bias

Describing the impact of the brief increase to the system's accuracy setting, the NPCC documents state: “The change significantly reduces the effect of bias across protected characteristics of race, generation and gender but had a significant negative impact on police efficiency”. The documents further note that forces complained that “a previously useful tool returned outcomes of questionable value”.

Broader Rollout Plans

Meanwhile, the government has opened a ten-week consultation on its plans to widen the use of biometric scanning systems. Policing minister the relevant minister has described the tool as the “most significant advance since genetic fingerprinting”.

Criticism from Advisors and Monitors

The chair of a police oversight board, chair of the independent scrutiny and oversight board for the national policing equality strategy, said: “There was very little discussion in race action plan meetings of the facial recognition rollout despite obvious cross-over with the strategy's goals.

“These revelations show yet again that the anti-racism commitments the police has undertaken through the equality initiative are not being translated into wider practice. Our reports have cautioned that new technologies are being rolled out in a context where ethnic inequalities, inadequate oversight and faulty information gathering already persist.

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

Home Office Response

A government representative said: “The Home Office takes the conclusions of the study with utmost gravity and we have already taken action. A updated software has been externally evaluated and procured, which has no statistically significant bias. It will be tested in the coming months and will be subject to further assessment.

“The foremost aim is protecting the public. This gamechanging technology will assist officers to apprehend and prosecute offenders. There is officer review in every step of the procedure and no arrest or charge would be taken without specialist personnel meticulously examining the output.”