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Police forces across the United Kingdom successfully lobbied to deploy a facial recognition system acknowledged as discriminatory against females, youths, and individuals from ethnic minority groups, after complaining that a more accurate version generated fewer investigative leads.

How the System Works

British police use the police national database (PND) to conduct retrospective facial recognition searches. This process entails comparing a “probe image” of a suspect against a database of more than 19 million mugshots to identify potential matches.

Admitted Bias

The Home Office admitted last week that the system was biased. This acknowledgment followed a review by the government's National Physical Laboratory determined it misidentified Black and Asian people and females at significantly higher rates than white men. The Home Office said it “took steps on the findings”.

“This raises the question of whether this technology only becomes effective if users accept biases in ethnicity and gender. Operational ease is a poor argument for overriding basic freedoms.”

Known Issue

Official papers reveal that this discriminatory flaw has been recognized for over twelve months. Furthermore, law enforcement argued to overturn an initial decision that was designed to address the problem.

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

A Reversed Decision

In response, the national police leadership body mandated that the accuracy setting required for potential matches be increased to a level where the disparity was greatly diminished.

However, this decision was overturned the next month following complaints from police that the adjusted system was producing fewer “useful lines of inquiry”. NPCC documents indicate the higher threshold cut the proportion of searches resulting in possible identifications from over half to a just under 15%.

Severe Disparities

Although the Home Office and NPCC refused to say what setting is currently used, the latest NPL study discovered the system could generate false positives for Black women almost 100 times more often than for white women at certain settings.

The ministry commented on these results: “The testing 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 brief increase to the system's accuracy setting, the NPCC documents note: “This adjustment greatly lessens the effect of bias across legally safeguarded attributes of race, generation and gender but had a substantially detrimental effect on operational effectiveness”. The papers add that forces complained that “a once effective tactic now delivered outcomes of questionable value”.

Wider Implementation Proposals

Meanwhile, the government has opened a two-and-a-half-month public review on its plans to expand the use of facial recognition technology. Policing minister the relevant minister has labeled the technology as the “most significant advance since DNA matching”.

Expert and Oversight Concerns

Abimbola Johnson, chair of the advisory panel for the police race action plan, commented: “There was very little consideration in race action plan meetings of the facial recognition rollout despite obvious cross-over with the strategy's goals.

“This disclosure show yet again that the pledges to combat discrimination the police has made via the equality initiative are not being translated into broader operations. Our reports have cautioned that innovative tools are being implemented in a context where racial disparities, inadequate oversight and faulty information gathering continue to exist.

“All deployment of this technology must meet strict national standards, be subject to external review, and demonstrate it reduces rather than exacerbates racial disparity.”

Home Office Response

A Home Office spokesperson said: “We takes the findings of the study seriously and we have implemented changes. A updated software has been independently tested and acquired, which has demonstrated no measurable discrimination. It will be trialled in the coming months and will be undergo evaluation.

“The foremost aim is ensuring public safety. This gamechanging technology will support police to apprehend and prosecute offenders. There is officer review in each stage of the procedure and no arrest or charge would be taken without trained officers carefully reviewing the output.”