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Law enforcement agencies across the UK successfully lobbied to deploy a face scanning system acknowledged as discriminatory against females, youths, and members of ethnic minority groups, following complaints that a more accurate version generated fewer investigative leads.

How the System Works

UK forces utilize the national police database to carry out retrospective facial recognition searches. This process entails comparing a “probe image” of a suspect against a repository of over 19 million custody photos to find possible hits.

Acknowledged Discrimination

The Home Office conceded last week that the technology was flawed. This admission came after a study by the National Physical Laboratory (NPL) found it incorrectly matched people of Black and Asian heritage and females at significantly higher rates than Caucasian males. The ministry stated it “had acted on the findings”.

“It prompts the question of whether facial recognition only becomes useful if users tolerate biases in race and gender. Operational ease is a weak argument for overriding fundamental rights.”

Known Issue

Internal documents show that this discriminatory flaw has been recognized for more than a year. Furthermore, police forces argued to overturn an initial decision that was intended to mitigate the problem.

Police bosses were informed of the system's bias in September 2024. The Home Office-commissioned NPL review found the system was had a higher probability to produce incorrect matches for photos of 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 confidence threshold required for possible hits be increased to a point where the disparity was greatly diminished.

However, this directive was reversed the following month following complaints from police that the adjusted system was generating fewer “useful lines of inquiry”. NPCC documents show the stricter setting cut the proportion of queries resulting in potential matches from 56% to a mere 14%.

Profound Inequalities

Although the Home Office and NPCC refused to say what threshold is now in operation, the latest NPL study found the system could generate false positives for Black women nearly a hundred times more often than for white women at certain settings.

The Home Office commented on these findings: “The testing identified that in a limited set of circumstances the software is more likely to incorrectly include some population segments in its match reports.”

Operational Effectiveness vs. Bias

Describing the impact of the temporary raise to the system's confidence threshold, the NPCC documents note: “This adjustment greatly lessens the impact of discrimination across protected characteristics of race, generation and gender but had a substantially detrimental effect on operational effectiveness”. The documents add that forces argued that “a previously useful tool now delivered outcomes of questionable value”.

Broader Rollout Plans

Meanwhile, the UK administration has launched a ten-week public review on its proposals to widen the use of biometric scanning systems. The minister for police Sarah Jones has described the technology as the “biggest breakthrough since DNA matching”.

Expert and Oversight Concerns

The chair of a police oversight board, head of the independent scrutiny and oversight board for the national policing equality strategy, commented: “There was very little consideration through equality strategy sessions of the technology deployment despite clear relevance with the strategy's goals.

“These revelations show yet again that the anti-racism commitments policing has undertaken through the equality initiative are failing to be integrated into wider practice. Our reports have warned that new technologies are being rolled out in a context where racial disparities, weak scrutiny and poor data collection continue to exist.

“Any use of this technology must meet rigorous official guidelines, be independently scrutinised, and prove it reduces rather than compounds racial disparity.”

Home Office Response

A Home Office spokesperson said: “The Home Office treat the conclusions of the study with utmost gravity and we have implemented changes. A new algorithm has been independently tested and procured, which has no statistically significant bias. It will be tested in the coming months and will be undergo evaluation.

“The foremost aim is protecting the public. This gamechanging technology will assist police to apprehend and prosecute offenders. There is human involvement in every step of the process and no arrest or charge would be taken without trained officers carefully reviewing the results.”