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Police forces across the UK successfully lobbied to deploy a facial recognition system acknowledged as discriminatory against females, youths, and individuals from minority ethnic backgrounds, after complaining that a more accurate version produced fewer potential suspects.

The Technology in Practice

British police utilize the police national database (PND) to conduct retrospective facial recognition searches. This process involves comparing a reference photograph of a suspect against a repository of more than 19 million custody photos to identify potential matches.

Admitted Bias

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

“It prompts the issue of whether this technology only becomes useful if users tolerate discrimination in race and sex. Convenience is a poor argument for overriding fundamental rights.”

Known Issue

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

Police bosses were notified of the algorithmic discrimination in September 2024. The Home Office-commissioned NPL review found the system was had a higher probability to suggest incorrect matches for images depicting females, individuals of Black ethnicity, and those under 40 years old.

A Reversed Decision

In response, the national police leadership body ordered that the confidence threshold required for possible hits be increased to a level where the bias was greatly diminished.

However, this directive was reversed the next month following complaints from police that the adjusted system was generating a lower number of “useful lines of inquiry”. NPCC documents indicate the higher threshold reduced the proportion of searches resulting in possible identifications from over half to a just under 15%.

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 generate false positives for Black women almost 100 times more often than for Caucasian women at certain settings.

The ministry commented on these results: “Our evaluation found that in a limited set of circumstances the software is more likely to incorrectly include some population segments in its search results.”

Operational Effectiveness vs. Bias

Outlining the impact of the temporary raise to the system's accuracy setting, the NPCC documents state: “The change greatly lessens the impact of bias across protected characteristics of race, age and sex but had a substantially detrimental effect on operational effectiveness”. The documents add that police units argued that “a once effective tactic now delivered outcomes of limited benefit”.

Broader Rollout Plans

Meanwhile, the government has opened a ten-week public review on its plans to expand the use of facial recognition technology. The minister for police the relevant minister has described the tool as the “most significant advance since DNA matching”.

Expert and Oversight Concerns

Abimbola Johnson, head of the independent scrutiny and oversight board for the national policing equality strategy, commented: “There was scant consideration in race action plan meetings of the technology deployment despite obvious cross-over with the strategy's goals.

“These revelations demonstrate once again that the pledges to combat discrimination policing has made via the equality initiative are not being translated into wider practice. Independent assessments have cautioned that innovative tools are being rolled out in a landscape where racial disparities, weak scrutiny and poor data collection already persist.

“All deployment of this technology must meet strict national standards, be independently scrutinised, and demonstrate it reduces rather than compounds ethnic bias.”

Official Statement

A Home Office spokesperson said: “The Home Office takes the conclusions of the study with utmost gravity and we have already taken action. A new algorithm has been independently tested and procured, which has demonstrated no measurable discrimination. It will be trialled early next year and will be undergo evaluation.

“The foremost aim is ensuring public safety. This revolutionary tool will support officers to apprehend and prosecute offenders. There is officer review in each stage of the procedure and no arrest or charge would be pursued without trained officers meticulously examining the output.”