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Law enforcement agencies across the UK successfully lobbied to use a facial recognition system known to be biased against females, youths, and members of minority ethnic backgrounds, after complaining that a more accurate version generated a reduced number of potential suspects.

How the System Works

British police use the national police database to conduct retrospective facial recognition searches. This procedure entails comparing a reference photograph of a suspect against a database of over 19 million custody photos to identify potential matches.

Acknowledged Discrimination

The UK interior ministry admitted last week that the system was biased. This admission followed a study by the National Physical Laboratory (NPL) determined it misidentified Black and Asian people and females at significantly higher rates than white men. The ministry said it “took steps on the findings”.

“It prompts the issue of whether this technology only becomes effective if users tolerate discrimination in ethnicity and sex. Operational ease is a weak argument for disregarding fundamental rights.”

Long-Standing Problem

Internal documents reveal that this bias has been recognized for over twelve months. Furthermore, law enforcement argued to overturn an initial decision that was designed to address the problem.

Police bosses were notified of the system's bias in late 2024. The government-ordered NPL review concluded the system was more likely to suggest false positives for photos of females, individuals of Black ethnicity, and those aged 40 and under.

A Reversed Decision

In reaction, the National Police Chiefs’ Council (NPCC) mandated that the confidence threshold required for potential matches be raised to a level where the bias was significantly reduced.

However, this directive was overturned the next month following complaints from police that the adjusted system was producing fewer “investigative leads”. Internal records show the higher threshold cut the number of queries that yielded potential matches from over half to a mere under 15%.

Profound Inequalities

Although the Home Office and NPCC declined to specify what setting is currently used, the latest independent review found the system could produce incorrect matches for Black women nearly a hundred times more often than for Caucasian women at certain settings.

The ministry commented on these findings: “Our evaluation found that in a limited set of circumstances the algorithm is more likely to wrongly flag some demographic groups in its search results.”

Balancing Utility and Fairness

Outlining the effect of the brief increase to the system's accuracy setting, the NPCC documents state: “This adjustment greatly lessens the effect of bias across protected characteristics of race, generation and gender but had a significant negative impact on operational effectiveness”. The papers further note that forces argued that “a once effective tactic now delivered results of limited benefit”.

Broader Rollout Plans

Meanwhile, the government has launched a two-and-a-half-month consultation on its plans to widen the use of facial recognition technology. Policing minister the relevant minister has described the technology as the “most significant advance since DNA matching”.

Expert and Oversight Concerns

The chair of a police oversight board, head of the advisory panel for the police race action plan, commented: “There was very little consideration through equality strategy sessions of the facial recognition rollout even with obvious cross-over with the strategy's goals.

“These revelations show once again that the anti-racism commitments policing has undertaken through the race action plan are failing to be integrated into broader operations. Independent assessments have warned that new technologies are being implemented in a context where racial disparities, inadequate oversight and poor data collection already persist.

“All deployment of this technology must adhere to rigorous official guidelines, be independently scrutinised, and prove it diminishes rather than exacerbates ethnic bias.”

Home Office Response

A government representative stated: “The Home Office takes the findings of the study seriously and we have implemented changes. A new algorithm has been externally evaluated and acquired, which has no statistically significant bias. It will be tested in the coming months and will be undergo further assessment.

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