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Police forces across the UK effectively campaigned to use a face scanning system known to be discriminatory against females, young people, and individuals from ethnic minority groups, after complaining that a more accurate version produced fewer potential suspects.

The Technology in Practice

British police utilize the police national database (PND) to carry out retrospective facial recognition searches. This procedure involves comparing a reference photograph of a person of interest against a repository of over 19 million mugshots to identify possible hits.

Admitted Bias

The UK interior ministry conceded last week that the technology was flawed. This admission followed a review by the National Physical Laboratory (NPL) found it misidentified Black and Asian people and women at much greater frequency than Caucasian males. The Home Office said it “had acted on the findings”.

“It prompts the issue of whether facial recognition only becomes useful if users accept biases in race and gender. Operational ease is a weak argument for overriding basic freedoms.”

Known Issue

Internal documents reveal that this discriminatory flaw has been known about for more than a year. Furthermore, law enforcement lobbied to reverse an initial decision that was designed to mitigate the problem.

Senior officers were notified of the algorithmic discrimination in September 2024. The government-ordered NPL review found the system was more likely to suggest incorrect matches for photos of women, individuals of Black ethnicity, and those aged 40 and under.

A Reversed Decision

In response, the National Police Chiefs’ Council (NPCC) ordered that the accuracy setting required for potential matches be raised to a point where the disparity was significantly reduced.

However, this directive was overturned the next month following complaints from police that the adjusted system was producing a lower number of “investigative leads”. Internal records show the higher threshold reduced the number of searches that yielded potential matches from over half to a mere 14%.

Profound Inequalities

Although the Home Office and NPCC refused to say what setting is now in operation, the latest NPL study discovered the system could generate incorrect matches for Black women almost 100 times more frequently than for Caucasian women at certain settings.

The Home Office commented on these findings: “Our evaluation found that in a limited set of circumstances the algorithm is has a greater tendency to wrongly flag some demographic groups in its match reports.”

Operational Effectiveness vs. Bias

Describing the effect of the temporary raise to the system's accuracy setting, the NPCC documents note: “This adjustment greatly lessens the effect of discrimination across protected characteristics of race, age and sex but had a significant negative impact on police efficiency”. The documents add that police units complained that “a previously useful tool now delivered outcomes of questionable value”.

Wider Implementation Proposals

Meanwhile, the government has launched a two-and-a-half-month public review on its proposals to widen the use of facial recognition technology. The minister for police Sarah Jones has described the technology as the “most significant advance since genetic fingerprinting”.

Expert and Oversight Concerns

Abimbola Johnson, chair of the independent scrutiny and oversight board for the police race action plan, commented: “There was scant consideration in equality strategy sessions of the technology deployment despite obvious cross-over with the plan’s concerns.

“These revelations show once again that the anti-racism commitments policing has undertaken through the race action plan are not being translated into wider practice. Independent assessments have warned that new technologies are being implemented in a context where ethnic inequalities, weak scrutiny and faulty information gathering already persist.

“All deployment of this technology must meet rigorous official guidelines, be subject to external review, and prove it diminishes rather than compounds ethnic bias.”

Official Statement

A Home Office spokesperson said: “We takes the conclusions of the report with utmost gravity and we have already taken action. A new algorithm has been independently tested and procured, which has no statistically significant bias. It will be tested early next year and will be subject to further assessment.

“The foremost aim is ensuring public safety. This gamechanging technology 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 taken without specialist personnel meticulously examining the output.”