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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 members of minority ethnic backgrounds, following complaints that a more accurate version produced fewer potential suspects.

The Technology in Practice

British police utilize the national police database to carry out searches using historical face recognition. This procedure involves matching a reference photograph of a person of interest against a database of over 19 million custody photos to identify potential matches.

Admitted Bias

The Home Office conceded last week that the system was flawed. This admission came after a review by the National Physical Laboratory (NPL) determined it incorrectly matched Black and Asian people and women at much greater frequency than Caucasian males. The Home Office stated it “had acted on the findings”.

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

Known Issue

Official papers show that this bias has been known about for over twelve months. Furthermore, police forces argued to overturn an earlier ruling that was designed to address the problem.

Police bosses were informed of the system's bias in late 2024. The Home Office-commissioned laboratory study concluded the system was more likely to produce false positives for images depicting females, individuals of Black ethnicity, and those under 40 years old.

A Policy U-Turn

In reaction, the National Police Chiefs’ Council (NPCC) ordered that the confidence threshold required for possible hits be increased to a level where the bias was greatly diminished.

However, this decision was overturned the next month after forces complained that the modified technology was generating fewer “useful lines of inquiry”. Internal records show the higher threshold reduced the proportion of searches resulting in potential matches from over half to a just 14%.

Profound Inequalities

Although the authorities refused to say what setting is currently used, the latest NPL study discovered the system could generate false positives for Black women nearly a hundred times more frequently than for Caucasian women at specific configurations.

The Home Office commented on these results: “The testing identified that in a specific scenarios the software is more likely to incorrectly include some demographic groups in its search results.”

Balancing Utility and Fairness

Outlining the impact of the brief increase to the system's accuracy setting, the NPCC documents state: “The change greatly lessens the impact of discrimination across legally safeguarded attributes of race, age and sex but had a significant negative impact on operational effectiveness”. The papers further note that police units complained that “a once effective tactic returned results of questionable value”.

Wider Implementation Proposals

Meanwhile, the government has opened a ten-week consultation on its plans to expand the use of facial recognition technology. Policing minister the relevant minister has described the tool 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, said: “There was very little consideration in 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 made through the equality initiative are not being translated into wider practice. Our reports have cautioned that innovative tools are being implemented in a context where ethnic inequalities, inadequate oversight and faulty information gathering already persist.

“Any use of facial recognition must meet rigorous official guidelines, be independently scrutinised, and demonstrate it reduces rather than exacerbates ethnic bias.”

Home Office Response

A government representative said: “We takes the conclusions of the study with utmost gravity and we have implemented changes. A updated software has been externally evaluated and procured, which has demonstrated no measurable discrimination. It will be trialled early next year and will be subject to further assessment.

“The foremost aim is protecting the public. This revolutionary tool will assist police to apprehend and prosecute offenders. There is human involvement in each stage of the procedure and no arrest or charge would be pursued without specialist personnel carefully reviewing the output.”