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Police forces across the United Kingdom successfully lobbied to deploy a face scanning system known to be discriminatory against women, young people, and members of ethnic minority groups, following complaints that a less biased version generated a reduced number of potential suspects.

The Technology in Practice

British police use the police national database (PND) to conduct retrospective facial recognition searches. This procedure involves comparing a “probe image” of a suspect against a database of over 19 million mugshots to identify possible hits.

Acknowledged Discrimination

The UK interior ministry admitted last week that the technology was flawed. This acknowledgment came after a review by the National Physical Laboratory (NPL) determined it incorrectly matched people of Black and Asian heritage 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 this technology only becomes effective if users tolerate discrimination in race and gender. Convenience is a poor argument for overriding basic freedoms.”

Known Issue

Official papers show that this discriminatory flaw has been recognized for over twelve months. Furthermore, law enforcement argued to overturn an initial decision that was designed to mitigate the problem.

Senior officers were informed of the algorithmic discrimination in September 2024. The Home Office-commissioned laboratory study found the system was more likely to suggest incorrect matches for photos of females, individuals of Black ethnicity, and those under 40 years old.

A Reversed Decision

In response, the National Police Chiefs’ Council (NPCC) ordered that the accuracy setting required for possible hits be increased to a level where the disparity was significantly reduced.

However, this directive was reversed the next month following complaints from police that the adjusted system was generating a lower number of “investigative leads”. Internal records show the higher threshold cut the proportion of searches that yielded possible identifications from 56% to a mere under 15%.

Severe Disparities

Although the authorities declined to specify what threshold is currently used, the recent independent review found the system could produce incorrect matches for Black women almost 100 times more frequently than for white women at certain settings.

The Home Office stated on these results: “The testing found that in a specific scenarios the software is has a greater tendency to wrongly flag some demographic groups in its match reports.”

Operational Effectiveness vs. Bias

Outlining the effect of the brief increase to the system's accuracy setting, the police records note: “The change greatly lessens the effect of bias across protected characteristics of ethnicity, age and gender but had a substantially detrimental effect on operational effectiveness”. The papers add that police units complained that “a once effective tactic now delivered results of questionable value”.

Wider Implementation Proposals

Meanwhile, the government has opened a ten-week public review on its proposals to expand the use of biometric scanning systems. The minister for police 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 independent scrutiny and oversight board for the police race action plan, commented: “There was scant consideration through equality strategy sessions of the technology deployment despite clear relevance with the plan’s concerns.

“These revelations demonstrate yet again that the pledges to combat discrimination policing has undertaken through the equality initiative are not being translated into wider practice. Independent assessments have cautioned that innovative tools are being rolled out in a context where ethnic inequalities, weak scrutiny and poor data collection continue to exist.

“Any use of this technology must meet rigorous official guidelines, be subject to external review, and demonstrate it reduces rather than exacerbates racial disparity.”

Official Statement

A government representative said: “The Home Office takes the conclusions of the study seriously 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 early next year and will be undergo evaluation.

“Our priority is protecting the public. This gamechanging technology will support 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.”