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Law enforcement agencies across the United Kingdom successfully lobbied to use a face scanning system known to be biased against females, young people, and individuals from ethnic minority groups, after complaining that a less biased version produced fewer investigative leads.

How the System Works

UK forces utilize the national police database to carry out searches using historical face recognition. This process entails matching a reference photograph of a suspect against a database of more than 19 million custody photos to identify potential matches.

Acknowledged Discrimination

The UK interior ministry conceded last week that the technology was biased. This admission came after a study by the government's National Physical Laboratory found it incorrectly matched Black and Asian people and females at significantly higher rates than white men. The Home Office stated it “had acted on the findings”.

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

Long-Standing Problem

Official papers reveal that this discriminatory flaw has been known about for more than a year. Furthermore, police forces lobbied to reverse an initial decision that was designed to address the problem.

Senior officers were notified of the algorithmic discrimination in September 2024. The Home Office-commissioned NPL review concluded the system was more likely to suggest incorrect matches for images depicting women, Black people, and those aged 40 and under.

A Reversed Decision

In reaction, the National Police Chiefs’ Council (NPCC) mandated that the accuracy setting 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 producing a lower number of “investigative leads”. NPCC documents show the higher threshold cut the number of queries resulting in potential matches from over half to a mere 14%.

Severe Disparities

Although the authorities refused to say what threshold is now in operation, the recent independent review discovered the system could generate incorrect matches for women of Black heritage almost 100 times more often than for white women at certain settings.

The ministry commented on these results: “The testing found that in a limited set of circumstances the algorithm is more likely to incorrectly include some population segments in its match reports.”

Operational Effectiveness vs. Bias

Describing the impact of the brief increase to the system's accuracy setting, the police records note: “The change greatly lessens the effect of discrimination across protected characteristics of race, generation 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”.

Broader Rollout Plans

Meanwhile, the government has opened a two-and-a-half-month consultation on its plans to widen the use of biometric scanning systems. The minister for police Sarah Jones has described the technology as the “most significant advance since genetic fingerprinting”.

Criticism from Advisors and Monitors

The chair of a police oversight board, head of the advisory panel for the national policing equality strategy, commented: “We observed scant discussion through equality strategy sessions of the facial recognition rollout even with obvious cross-over with the plan’s concerns.

“These revelations demonstrate once again that the anti-racism commitments policing has undertaken through the equality initiative are not being translated into broader operations. Our reports have warned that innovative tools are being implemented in a context where racial disparities, inadequate oversight and faulty information gathering already persist.

“Any use of this technology must adhere to strict national standards, be independently scrutinised, and prove it reduces rather than compounds ethnic bias.”

Home Office Response

A Home Office spokesperson stated: “The Home Office treat the findings of the report seriously and we have already taken action. A new algorithm has been externally evaluated and acquired, which has no statistically significant bias. It will be trialled in the coming months and will be subject to evaluation.

“Our priority is protecting the public. This revolutionary tool will support officers to apprehend and prosecute offenders. There is officer review in each stage of the process and no arrest or charge would be pursued without specialist personnel carefully reviewing the results.”