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Police forces across the United Kingdom successfully lobbied to use a face scanning system known to be discriminatory against females, young people, and members of minority ethnic backgrounds, following complaints that a more accurate version generated fewer potential suspects.

How the System Works

British police use the national police database to carry out searches using historical face recognition. This procedure involves matching a reference photograph of a suspect against a database of over 19 million mugshots to identify possible hits.

Acknowledged Discrimination

The Home Office admitted last week that the system was biased. This acknowledgment followed a study by the government's National Physical Laboratory determined it misidentified people of Black and Asian heritage and women at much greater frequency than Caucasian males. The ministry said it “had acted on the findings”.

“This raises the issue of whether facial recognition only becomes effective if users accept biases in race and sex. Convenience is a poor argument for overriding fundamental rights.”

Long-Standing Problem

Official papers show that this bias has been known about for over twelve months. Furthermore, law enforcement lobbied to reverse an earlier ruling that was intended to address the problem.

Senior officers were informed of the system's bias in late 2024. The Home Office-commissioned NPL review concluded the system was had a higher probability to suggest incorrect matches for images depicting women, Black people, and those aged 40 and under.

A Reversed Decision

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

However, this directive was reversed the following month following complaints from police that the modified technology was generating fewer “investigative leads”. NPCC documents indicate the stricter setting reduced the proportion of searches that yielded potential matches from 56% to a just under 15%.

Profound Inequalities

Although the Home Office and NPCC declined to specify what setting is now in operation, the latest NPL study found the system could produce incorrect matches for women of Black heritage almost 100 times more often than for white women at certain settings.

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

Operational Effectiveness vs. Bias

Describing the effect of the temporary raise to the system's confidence threshold, the NPCC documents note: “This adjustment greatly lessens the impact of bias across legally safeguarded attributes of ethnicity, generation and sex but had a substantially detrimental effect on operational effectiveness”. The documents add that police units complained that “a previously useful tool returned results of questionable value”.

Wider Implementation Proposals

Meanwhile, the government has opened a two-and-a-half-month consultation on its plans to expand the use of facial recognition technology. The minister for police Sarah Jones has labeled the technology as the “biggest breakthrough since DNA matching”.

Criticism from Advisors and Monitors

Abimbola Johnson, chair of the independent scrutiny and oversight board for the police race action plan, said: “There was scant consideration through race action plan meetings of the technology deployment despite clear relevance with the strategy's goals.

“These revelations demonstrate once again that the pledges to combat discrimination the police has undertaken via 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 compounds racial disparity.”

Home Office Response

A Home Office spokesperson stated: “We takes the findings of the report with utmost gravity and we have implemented changes. A updated software has been externally evaluated and procured, which has no statistically significant bias. It will be trialled in the coming months and will be undergo further assessment.

“Our priority is ensuring public safety. This revolutionary tool will support police to put criminals and rapists behind bars. There is officer review in every step of the procedure and no further action would be taken without trained officers meticulously examining the output.”