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Law enforcement agencies across the UK effectively campaigned to deploy a face scanning system known to be discriminatory against females, youths, and individuals from ethnic minority groups, after complaining that a more accurate version produced fewer investigative leads.

The Technology in Practice

UK forces use the national police database to conduct searches using historical face recognition. This procedure involves comparing a reference photograph of a person of interest against a repository of more than 19 million mugshots to identify possible hits.

Admitted Bias

The Home Office admitted last week that the technology was flawed. This acknowledgment came after a review by the government's National Physical Laboratory determined it incorrectly matched Black and Asian people and females at much greater frequency than Caucasian males. The Home Office said it “took steps on the findings”.

“It prompts the issue of whether this technology only becomes useful if users tolerate biases in race 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 initial decision that was intended to mitigate the problem.

Senior officers were informed of the system's bias in September 2024. The Home Office-commissioned laboratory study found the system was had a higher probability to suggest incorrect matches for images depicting females, Black people, and those aged 40 and under.

A Reversed Decision

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

However, this directive was reversed the next month following complaints from police that the adjusted system was producing 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 mere 14%.

Severe Disparities

Although the authorities refused to say what threshold is now in operation, the latest NPL study discovered the system could produce false positives for women of Black heritage nearly a hundred times more frequently than for Caucasian women at certain settings.

The ministry commented on these findings: “Our evaluation found that in a specific scenarios the software is more likely to wrongly flag some demographic groups in its search results.”

Operational Effectiveness vs. Bias

Describing the impact of the temporary raise to the system's confidence threshold, the NPCC documents note: “The change significantly reduces the effect of bias across protected characteristics of race, age and sex but had a substantially detrimental effect on operational effectiveness”. The papers further note that forces complained that “a previously useful tool now delivered results of questionable value”.

Wider Implementation Proposals

Meanwhile, the UK administration has launched a two-and-a-half-month consultation on its proposals to expand the use of facial recognition technology. The minister for police Sarah Jones has described the tool as the “biggest breakthrough since DNA matching”.

Criticism from Advisors and Monitors

The chair of a police oversight board, chair of the independent scrutiny and oversight board for the police race action plan, said: “There was scant consideration in race action plan meetings of the facial recognition rollout even with obvious cross-over with the strategy's goals.

“This disclosure demonstrate once again that the pledges to combat discrimination policing has undertaken through the equality initiative are failing to be integrated into broader operations. Our reports have warned that new technologies are being rolled out in a landscape where racial disparities, weak scrutiny and faulty information gathering already persist.

“Any use 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 Home Office spokesperson stated: “We treat the findings of the study with utmost gravity and we have already taken action. A new algorithm has been independently tested and acquired, which has no statistically significant bias. It will be tested early next year and will be subject to evaluation.

“Our priority is ensuring public safety. This gamechanging technology will support police to put criminals and rapists behind bars. There is officer review in every step of the process and no arrest or charge would be taken without trained officers carefully reviewing the output.”