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Police forces across the UK successfully lobbied to use a face scanning system known to be biased against females, youths, and members of ethnic minority groups, following complaints that a less biased version produced fewer potential suspects.

How the System Works

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

Acknowledged Discrimination

The UK interior ministry conceded last week that the technology was flawed. This acknowledgment followed a review by the government's National Physical Laboratory found it incorrectly matched Black and Asian people and females at significantly higher rates than Caucasian males. The Home Office said it “took steps on the findings”.

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

Long-Standing Problem

Internal documents show that this bias has been known about for over twelve months. Furthermore, police forces argued to overturn an earlier ruling that was designed to address the problem.

Senior officers were informed of the system's bias in late 2024. The government-ordered 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) mandated that the confidence threshold required for possible hits be increased to a level where the disparity was greatly diminished.

However, this directive was reversed the following month after forces complained that the modified technology was producing fewer “investigative leads”. Internal records show the stricter setting cut the number of queries that yielded possible identifications from 56% to a mere 14%.

Severe Disparities

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

The ministry commented on these results: “Our evaluation found that in a limited set of circumstances the algorithm is has a greater tendency to wrongly flag some demographic groups in its search results.”

Operational Effectiveness vs. Bias

Describing the impact of the brief increase to the system's accuracy setting, the NPCC documents state: “The change greatly lessens the impact of discrimination across protected characteristics of ethnicity, age and sex but had a significant negative impact on operational effectiveness”. The papers further note that forces complained that “a once effective tactic returned outcomes of limited benefit”.

Wider Implementation Proposals

Meanwhile, the government has launched a two-and-a-half-month public review on its plans to expand the use of biometric scanning systems. The minister for police Sarah Jones has labeled the tool as the “biggest breakthrough since genetic fingerprinting”.

Criticism from Advisors and Monitors

Abimbola Johnson, head of the advisory panel for the police race action plan, commented: “We observed very little discussion through equality strategy sessions of the technology deployment even with obvious cross-over with the strategy's goals.

“These revelations show yet again that the pledges to combat discrimination policing has made via the equality initiative are not being translated into broader operations. Independent assessments have cautioned that new technologies are being implemented in a context where ethnic inequalities, weak scrutiny and faulty information gathering continue to exist.

“Any use of facial recognition must adhere to strict national standards, be independently scrutinised, and demonstrate it diminishes rather than compounds ethnic bias.”

Home Office Response

A Home Office spokesperson said: “We treat the findings of the study with utmost gravity and we have implemented changes. A updated software has been independently tested and acquired, which has no statistically significant bias. It will be tested in the coming months and will be subject to further assessment.

“The foremost aim is ensuring public safety. This revolutionary tool will assist officers to put criminals and rapists behind bars. There is officer review in each stage of the procedure and no further action would be pursued without trained officers carefully reviewing the results.”