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Police forces across the UK successfully lobbied to deploy a face scanning system known to be discriminatory against women, youths, and members of minority ethnic backgrounds, following complaints that a more accurate version produced fewer investigative leads.

The Technology in Practice

British police utilize the police national database (PND) to carry out retrospective facial recognition searches. This procedure entails matching a “probe image” of a person of interest against a repository of over 19 million mugshots to identify potential matches.

Admitted Bias

The UK interior ministry conceded last week that the system was flawed. This acknowledgment came after a study by the government's National Physical Laboratory determined it incorrectly matched Black and Asian people and women at much greater frequency than white men. The ministry said it “took steps on the findings”.

“This raises the question of whether this technology only becomes effective if users tolerate biases in ethnicity and sex. Operational ease is a poor argument for overriding fundamental rights.”

Long-Standing Problem

Internal documents reveal that this bias has been known about for over twelve months. Furthermore, law enforcement lobbied to reverse an initial decision that was designed to address the problem.

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

A Policy U-Turn

In response, the national police leadership body mandated that the confidence threshold required for possible hits be raised to a level where the disparity was greatly diminished.

However, this directive was overturned the following month after forces complained that the adjusted system was generating fewer “useful lines of inquiry”. Internal records show the higher threshold cut the proportion of queries resulting in potential matches from over half to a just under 15%.

Severe Disparities

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

The ministry commented on these results: “The testing identified that in a limited set of circumstances the software is more likely to incorrectly include some demographic groups in its match reports.”

Balancing Utility and Fairness

Outlining the impact of the brief increase to the system's confidence threshold, the NPCC documents note: “The change significantly reduces the impact of discrimination across legally safeguarded attributes of ethnicity, age and gender but had a substantially detrimental effect on operational effectiveness”. The papers add that police units complained that “a once effective tactic now delivered outcomes of limited benefit”.

Wider Implementation Proposals

Meanwhile, the government has opened a two-and-a-half-month public review on its plans to widen the use of facial recognition technology. Policing minister Sarah Jones has labeled the tool as the “biggest breakthrough since genetic fingerprinting”.

Expert and Oversight Concerns

Abimbola Johnson, head of the independent scrutiny and oversight board for the police race action plan, said: “We observed very little consideration in equality strategy sessions of the technology deployment despite obvious cross-over with the strategy's goals.

“This disclosure show yet again that the anti-racism commitments policing has undertaken via the race action plan are failing to be integrated into broader operations. Our reports have cautioned that innovative tools are being rolled out in a context where racial disparities, 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 exacerbates ethnic bias.”

Official Statement

A Home Office spokesperson said: “The Home Office takes the findings of the study with utmost gravity and we have implemented changes. A new algorithm has been externally evaluated and acquired, which has no statistically significant bias. It will be tested early next year and will be subject to evaluation.

“The foremost aim is ensuring public safety. This gamechanging technology will assist police to apprehend and prosecute offenders. There is officer review in every step of the process and no further action would be taken without trained officers meticulously examining the results.”