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Police forces across the UK successfully lobbied to deploy a facial recognition system known to be discriminatory against women, young people, and individuals from minority ethnic backgrounds, following complaints that a less biased version generated a reduced number of investigative leads.

How the System Works

British police utilize the national police database to carry out retrospective facial recognition searches. This process involves matching a “probe image” of a suspect against a database of more than 19 million mugshots to identify possible hits.

Admitted Bias

The Home Office conceded last week that the technology was flawed. This admission came after a review by the government's National Physical Laboratory determined it incorrectly matched Black and Asian people and females at significantly higher rates than white men. The ministry stated it “took steps on the findings”.

“It prompts the issue of whether facial recognition only becomes useful if users tolerate biases in ethnicity and sex. Operational ease is a weak argument for overriding fundamental rights.”

Long-Standing Problem

Internal documents show that this discriminatory flaw 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 notified of the algorithmic discrimination in September 2024. The Home Office-commissioned laboratory study found the system was had a higher probability to suggest incorrect matches for photos of females, individuals of Black ethnicity, and those aged 40 and under.

A Reversed Decision

In response, the National Police Chiefs’ Council (NPCC) 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 after forces complained that the modified technology was producing fewer “useful lines of inquiry”. Internal records indicate the higher threshold reduced the proportion of queries that yielded potential matches from 56% to a just under 15%.

Profound Inequalities

Although the Home Office and NPCC refused to say what setting is currently used, the latest NPL study found the system could generate incorrect matches for Black women nearly a hundred times more often than for white women at certain settings.

The ministry commented on these findings: “Our evaluation found that in a specific scenarios the algorithm is has a greater tendency to wrongly flag some population segments in its search results.”

Balancing Utility and Fairness

Describing the effect of the temporary raise to the system's confidence threshold, the police records note: “The change greatly lessens the effect of bias across legally safeguarded attributes of race, generation and sex but had a significant negative impact on police efficiency”. The papers add that police units argued that “a once effective tactic now delivered outcomes of limited benefit”.

Wider Implementation Proposals

Meanwhile, the government has launched a two-and-a-half-month consultation on its proposals to expand the use of facial recognition technology. Policing minister the relevant minister has described the technology as the “biggest breakthrough since DNA matching”.

Expert and Oversight Concerns

Abimbola Johnson, chair of the advisory panel for the police race action plan, said: “We observed very little consideration in race action plan meetings of the facial recognition rollout despite obvious cross-over with the plan’s concerns.

“These revelations show once again that the pledges to combat discrimination policing has undertaken through the race action plan are not being translated into broader operations. Independent assessments have warned that innovative tools are being implemented in a landscape where ethnic inequalities, weak scrutiny and faulty information gathering already persist.

“All deployment of this technology must meet strict national standards, be subject to external review, and prove it diminishes rather than exacerbates ethnic bias.”

Official Statement

A government representative stated: “We takes the conclusions of the study with utmost gravity and we have already taken action. A updated software has been independently tested and procured, which has no statistically significant bias. It will be trialled early next year and will be undergo evaluation.

“The foremost aim is protecting the public. This revolutionary tool will support officers to put criminals and rapists behind bars. There is officer review in every step of the procedure and no arrest or charge would be taken without specialist personnel meticulously examining the output.”