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Police forces across the UK successfully lobbied to deploy a face scanning system acknowledged as biased against females, young people, and individuals from ethnic minority groups, following complaints that a more accurate version generated fewer potential suspects.

The Technology in Practice

British police utilize the police national database (PND) to conduct retrospective facial recognition searches. This procedure involves comparing a “probe image” of a person of interest against a repository of more than 19 million mugshots to find possible hits.

Acknowledged Discrimination

The Home Office conceded last week that the system was biased. This acknowledgment followed a review by the government's National Physical Laboratory found it incorrectly matched people of Black and Asian heritage and women at much greater frequency than Caucasian males. The ministry stated it “took steps on the findings”.

“It prompts the question of whether this technology only becomes useful if users accept biases in race and sex. Operational ease is a poor argument for overriding fundamental rights.”

Long-Standing Problem

Internal documents show that this discriminatory flaw has been known about for more than a year. Furthermore, law enforcement argued to overturn an earlier ruling that was designed to mitigate the problem.

Senior officers were informed of the algorithmic discrimination in late 2024. The Home Office-commissioned NPL review found the system was had a higher probability to suggest false positives for photos of females, Black people, and those under 40 years old.

A Reversed Decision

In reaction, the National Police Chiefs’ Council (NPCC) mandated that the confidence threshold required for possible hits be increased to a level where the disparity was greatly diminished.

However, this directive was overturned the next month following complaints from police that the modified technology was generating a lower number of “investigative leads”. NPCC documents indicate the stricter setting reduced the proportion of queries resulting in possible identifications from 56% to a just under 15%.

Severe Disparities

Although the authorities refused to say what threshold is now in operation, the recent NPL study found the system could generate incorrect matches for women of Black heritage nearly a hundred times more often than for white women at specific configurations.

The ministry commented on these results: “Our evaluation found that in a limited set of circumstances the software is has a greater tendency to incorrectly include some demographic groups in its match reports.”

Operational Effectiveness vs. Bias

Describing the impact of the temporary raise to the system's confidence threshold, the police records note: “The change significantly reduces the impact of bias across legally safeguarded attributes of ethnicity, age and gender but had a significant negative impact on police efficiency”. The papers add that forces complained that “a previously useful tool now delivered outcomes of questionable value”.

Wider Implementation Proposals

Meanwhile, the UK administration has opened a ten-week consultation on its proposals to expand the use of biometric scanning systems. Policing minister Sarah Jones has labeled the technology as the “biggest breakthrough since genetic fingerprinting”.

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, commented: “We observed scant consideration in equality strategy sessions of the facial recognition rollout despite clear relevance with the strategy's goals.

“These revelations show yet again that the pledges to combat discrimination the police has made through the equality initiative are failing to be integrated into broader operations. Our reports have cautioned that innovative tools are being rolled out in a landscape where racial disparities, weak scrutiny and faulty information gathering continue to exist.

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

Official Statement

A Home Office spokesperson stated: “We takes the conclusions of the study seriously and we have implemented changes. A new algorithm has been externally evaluated and procured, which has demonstrated no measurable discrimination. It will be tested early next year and will be undergo further assessment.

“Our priority is protecting the public. This gamechanging technology will assist police to apprehend and prosecute offenders. There is human involvement in each stage of the procedure and no arrest or charge would be taken without specialist personnel meticulously examining the results.”