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Police forces across the UK effectively campaigned to use a facial recognition system known to be discriminatory against females, youths, and members of ethnic minority groups, after complaining that a less biased version produced fewer investigative leads.

The Technology in Practice

British police utilize the police national database (PND) to carry out retrospective facial recognition searches. This process involves comparing a reference photograph of a person of interest against a database of over 19 million custody photos to find potential matches.

Admitted Bias

The UK interior ministry conceded last week that the system was biased. This admission came after a study by the National Physical Laboratory (NPL) found it incorrectly matched Black and Asian people and females at much greater frequency than white men. The Home Office stated it “had acted on the findings”.

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

Known Issue

Official papers reveal that this discriminatory flaw has been known about for over twelve months. Furthermore, law enforcement lobbied to reverse an earlier ruling that was designed to mitigate the problem.

Police bosses were informed of the system's bias in September 2024. The government-ordered laboratory study found the system was more likely to suggest false positives for photos of women, Black people, and those aged 40 and under.

A Reversed Decision

In response, the National Police Chiefs’ Council (NPCC) ordered that the accuracy setting required for possible hits be raised to a point where the bias was greatly diminished.

However, this decision was reversed the next month after forces complained that the adjusted system was producing fewer “useful lines of inquiry”. Internal records show the stricter setting reduced the number of searches that yielded possible identifications from over half to a mere 14%.

Severe Disparities

Although the Home Office and NPCC refused to say what setting is now in operation, the recent NPL study found the system could produce false positives for Black women nearly a hundred times more often than for Caucasian women at certain settings.

The ministry stated on these results: “The testing identified that in a limited set of circumstances the algorithm is has a greater tendency to wrongly flag some population segments in its search results.”

Balancing Utility and Fairness

Outlining the impact of the temporary raise to the system's confidence threshold, the police records note: “This adjustment greatly lessens the effect of discrimination across legally safeguarded attributes of ethnicity, generation and sex but had a significant negative impact on police efficiency”. The documents add that forces complained that “a once effective tactic returned outcomes of limited benefit”.

Wider Implementation Proposals

Meanwhile, the UK administration has opened a two-and-a-half-month public review on its proposals to expand the use of facial recognition technology. The minister for police Sarah Jones has described the tool as the “biggest breakthrough since DNA matching”.

Expert and Oversight Concerns

Abimbola Johnson, chair of the advisory panel for the national policing equality strategy, said: “There was very little consideration through equality strategy sessions of the technology deployment even with clear relevance with the strategy's goals.

“This disclosure show once again that the pledges to combat discrimination policing has undertaken through the equality initiative are failing to be integrated into wider practice. Independent assessments have cautioned that innovative tools are being rolled out in a context where racial disparities, inadequate oversight and faulty information gathering continue to exist.

“All deployment of this technology must adhere to rigorous official guidelines, be subject to external review, and demonstrate it reduces rather than compounds racial disparity.”

Home Office Response

A government representative stated: “The Home Office takes the findings of the report with utmost gravity and we have already taken action. A updated software has been independently tested and acquired, which has demonstrated no measurable discrimination. It will be tested in the coming months and will be subject to further assessment.

“Our priority is ensuring public safety. This gamechanging technology will assist officers to apprehend and prosecute offenders. There is officer review in every step of the process and no arrest or charge would be pursued without specialist personnel carefully reviewing the results.”