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Police forces across the United Kingdom effectively campaigned to deploy a face scanning system known to be discriminatory against women, youths, and members of ethnic minority groups, following complaints that a more accurate version produced fewer potential suspects.

The Technology in Practice

UK forces use the police national database (PND) to carry out retrospective facial recognition searches. This procedure involves matching a reference photograph of a suspect against a repository of more than 19 million custody photos 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 government's National Physical Laboratory found it misidentified Black and Asian people and females at much greater frequency than white men. The ministry stated it “had acted on the findings”.

“This raises the question of whether facial recognition only becomes effective if users accept discrimination in ethnicity and sex. Operational ease is a poor argument for disregarding basic freedoms.”

Known Issue

Official papers show that this discriminatory flaw has been recognized for more than a year. Furthermore, law enforcement lobbied to reverse an initial decision that was intended to address the problem.

Senior officers were informed of the system's bias in September 2024. The government-ordered laboratory study found the system was had a higher probability to produce incorrect matches for images depicting women, Black people, and those aged 40 and under.

A Reversed Decision

In response, the National Police Chiefs’ Council (NPCC) mandated that the accuracy setting required for possible hits be increased to a point where the bias was significantly reduced.

However, this directive was overturned the following month after forces complained that the adjusted system was generating a lower number of “investigative leads”. NPCC documents show the higher threshold cut the proportion of queries that yielded potential matches from 56% to a just 14%.

Severe Disparities

Although the authorities declined to specify what setting is now in operation, the recent NPL study discovered the system could produce incorrect matches for women of Black heritage almost 100 times more often than for Caucasian women at specific configurations.

The ministry commented on these results: “Our evaluation found that in a specific scenarios the software is more likely to incorrectly include some demographic groups in its match reports.”

Balancing Utility and Fairness

Describing the effect of the temporary raise to the system's confidence threshold, the police records state: “The change significantly reduces the impact of bias across legally safeguarded attributes of race, age and sex but had a substantially detrimental effect on operational effectiveness”. The papers add that forces argued that “a once effective tactic returned outcomes of questionable value”.

Broader Rollout Plans

Meanwhile, the UK administration has opened a two-and-a-half-month public review on its plans to expand the use of facial recognition technology. The minister for police Sarah Jones has described the technology as the “most significant advance since DNA matching”.

Criticism from Advisors and Monitors

Abimbola Johnson, head of the independent scrutiny and oversight board for the national policing equality strategy, commented: “We observed scant consideration through race action plan meetings of the technology deployment even with obvious cross-over with the strategy's goals.

“These revelations demonstrate yet again that the anti-racism commitments the police has made via the equality initiative are failing to be integrated into wider practice. Independent assessments have warned that new technologies are being implemented in a context where ethnic inequalities, inadequate oversight and poor data collection continue to exist.

“All deployment of facial recognition must meet rigorous official guidelines, be independently scrutinised, and demonstrate it reduces rather than exacerbates racial disparity.”

Home Office Response

A government representative stated: “The Home Office takes the conclusions of the report with utmost gravity and we have already taken action. A updated software has been independently tested and procured, which has no statistically significant bias. It will be trialled early next year and will be subject to further assessment.

“Our priority is protecting the public. This gamechanging technology will support police to apprehend and prosecute offenders. There is human involvement in each stage of the procedure and no further action would be pursued without specialist personnel carefully reviewing the results.”