🔗 Share this article

Police forces across the United Kingdom effectively campaigned to use a face scanning system acknowledged as discriminatory against females, youths, and individuals from minority ethnic backgrounds, after complaining that a more accurate version produced a reduced number of potential suspects.

How the System Works

British police use the police national database (PND) to conduct searches using historical face recognition. This process involves comparing a “probe image” of a person of interest against a repository of more than 19 million custody photos to find possible hits.

Admitted Bias

The UK interior ministry conceded last week that the system was flawed. This admission followed a review by the National Physical Laboratory (NPL) found it misidentified people of Black and Asian heritage and females at much greater frequency than Caucasian males. The ministry stated it “had acted on the findings”.

“It prompts the issue of whether facial recognition only becomes useful if users tolerate discrimination in ethnicity and sex. Operational ease is a poor argument for disregarding basic freedoms.”

Long-Standing Problem

Internal documents show that this bias has been recognized for more than a year. Furthermore, law enforcement argued to overturn an initial decision that was intended to mitigate the problem.

Senior officers were informed of the algorithmic discrimination in September 2024. The government-ordered NPL review found the system was more likely to produce incorrect matches for images depicting females, individuals of Black ethnicity, and those under 40 years old.

A Policy U-Turn

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

However, this decision was overturned the next month after forces complained that the adjusted system was generating fewer “useful lines of inquiry”. Internal records indicate the higher threshold cut the number of queries that yielded potential matches from 56% to a just under 15%.

Profound Inequalities

Although the authorities refused to say what setting is currently used, the recent NPL study found the system could produce incorrect matches for women of Black heritage nearly a hundred times more often than for white women at specific configurations.

The Home Office commented on these findings: “Our evaluation found that in a limited set of circumstances the software is has a greater tendency to wrongly flag some population segments in its match reports.”

Operational Effectiveness vs. Bias

Outlining the effect of the brief increase to the system's confidence threshold, the police records state: “This adjustment significantly reduces the impact of discrimination across legally safeguarded attributes of ethnicity, age and gender but had a significant negative impact on operational effectiveness”. The documents further note that forces complained that “a once effective tactic returned outcomes of limited benefit”.

Broader Rollout Plans

Meanwhile, the government has launched a ten-week public review on its proposals to widen the use of facial recognition technology. The minister for police Sarah Jones has described the technology as the “most significant advance since DNA matching”.

Expert and Oversight Concerns

The chair of a police oversight board, chair of the independent scrutiny and oversight board for the national policing equality strategy, said: “We observed scant discussion in race action plan meetings of the technology deployment even with obvious cross-over with the plan’s concerns.

“These revelations show once again that the anti-racism commitments policing has undertaken via the race action plan are not being translated into broader operations. Independent assessments have warned that innovative tools are being implemented in a landscape where ethnic inequalities, weak scrutiny and faulty information gathering already persist.

“All deployment of facial recognition must adhere to strict national standards, be independently scrutinised, and demonstrate it reduces rather than exacerbates ethnic bias.”

Home Office Response

A government representative said: “The Home Office takes the findings of the report with utmost gravity and we have implemented changes. A new algorithm has been externally evaluated and acquired, which has demonstrated no measurable discrimination. It will be trialled in the coming months and will be undergo evaluation.

“The foremost aim is protecting the public. This gamechanging technology will support officers to put criminals and rapists behind bars. There is human involvement in every step of the process and no arrest or charge would be pursued without specialist personnel carefully reviewing the results.”