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Law enforcement agencies across the UK effectively campaigned to deploy a face scanning system acknowledged as biased against females, youths, and individuals from minority ethnic backgrounds, after complaining that a less biased version produced fewer investigative leads.

The Technology in Practice

British police use the national police database to carry out retrospective facial recognition searches. This process involves comparing a reference photograph of a person of interest against a database of over 19 million mugshots to identify possible hits.

Acknowledged Discrimination

The Home Office admitted last week that the system was flawed. This acknowledgment followed a study by the National Physical Laboratory (NPL) found it misidentified Black and Asian people and women at significantly higher rates than white men. The Home Office said it “had acted on the findings”.

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

Long-Standing Problem

Internal documents reveal that this discriminatory flaw has been recognized for more than a year. Furthermore, police forces argued to overturn an earlier ruling that was designed to mitigate the problem.

Senior officers were notified of the system's bias in late 2024. The government-ordered laboratory study found the system was more likely to suggest false positives for images depicting females, Black people, and those under 40 years old.

A Policy U-Turn

In reaction, the national police leadership body ordered that the accuracy setting required for potential matches be increased to a level where the disparity was greatly diminished.

However, this directive was overturned the following month following complaints from police that the adjusted system was generating a lower number of “useful lines of inquiry”. NPCC documents indicate the higher threshold cut the number of searches resulting in possible identifications from over half to a mere under 15%.

Severe Disparities

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

The Home Office stated on these results: “Our evaluation found that in a limited set of circumstances the software is more likely to wrongly flag some population segments in its match reports.”

Operational Effectiveness vs. Bias

Describing the effect of the temporary raise to the system's confidence threshold, the NPCC documents state: “This adjustment significantly reduces the effect of discrimination across legally safeguarded attributes of ethnicity, generation and sex but had a substantially detrimental effect on operational effectiveness”. The documents add that police units argued that “a once effective tactic returned outcomes of questionable value”.

Broader Rollout Plans

Meanwhile, the government has launched a ten-week public review on its plans to expand the use of biometric scanning systems. 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 police race action plan, commented: “We observed scant consideration through race action plan meetings of the technology deployment despite obvious cross-over with the plan’s concerns.

“This disclosure show yet again that the anti-racism commitments the police has undertaken through the race action plan are failing to be integrated into broader operations. Independent assessments have cautioned that new technologies are being rolled out in a context where ethnic inequalities, inadequate oversight and faulty information gathering already persist.

“All deployment of facial recognition must meet rigorous official guidelines, be independently scrutinised, and prove it diminishes rather than exacerbates ethnic bias.”

Official Statement

A Home Office spokesperson stated: “The Home Office treat the findings of the report with utmost gravity and we have implemented changes. A updated software has been externally evaluated and acquired, which has no statistically significant bias. It will be trialled in the coming months and will be undergo evaluation.

“Our priority is protecting the public. This gamechanging technology will support officers to apprehend and prosecute offenders. There is human involvement in every step of the procedure and no arrest or charge would be pursued without specialist personnel carefully reviewing the output.”