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Police forces across the United Kingdom effectively campaigned to use a face scanning system known to be biased against women, young people, and members of ethnic minority groups, following complaints that a more accurate version generated fewer investigative leads.

How the System Works

British police use the police national database (PND) to carry out searches using historical face recognition. This process involves comparing a reference photograph of a suspect against a repository of over 19 million custody photos to find possible hits.

Admitted Bias

The Home Office admitted last week that the technology was flawed. This acknowledgment followed a review by the government's National Physical Laboratory determined it misidentified people of Black and Asian heritage and women at much greater frequency than Caucasian males. The Home Office said it “had acted on the findings”.

“It prompts the question of whether facial recognition only becomes useful if users accept discrimination in race and sex. Operational ease is a weak argument for overriding fundamental rights.”

Known Issue

Internal documents reveal that this bias has been known about for over twelve months. Furthermore, police forces lobbied to reverse an earlier ruling that was intended to address the problem.

Senior officers were informed of the system's bias in September 2024. The Home Office-commissioned NPL review concluded the system was more likely to produce false positives for photos of females, individuals of Black ethnicity, and those aged 40 and under.

A Policy U-Turn

In reaction, the National Police Chiefs’ Council (NPCC) ordered that the accuracy setting required for potential matches be raised to a level where the bias was greatly diminished.

However, this directive was reversed the next month following complaints from police that the modified technology was producing a lower number of “useful lines of inquiry”. NPCC documents show the higher threshold reduced the proportion of searches that yielded possible identifications from over half to a just under 15%.

Profound Inequalities

Although the Home Office and NPCC declined to specify what threshold is currently used, the latest NPL study discovered the system could generate incorrect matches for women of Black heritage nearly a hundred times more frequently than for white women at specific configurations.

The Home Office commented on these findings: “Our evaluation identified that in a specific scenarios the software is more likely to wrongly flag 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 police records state: “The change greatly lessens the impact of discrimination across legally safeguarded attributes of race, generation and gender but had a significant negative impact on police efficiency”. The papers add that police units argued that “a previously useful tool now delivered results of questionable value”.

Broader Rollout Plans

Meanwhile, the government has opened a ten-week consultation on its proposals to expand the use of facial recognition technology. The minister for police Sarah Jones has labeled the tool as the “biggest breakthrough 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 national policing equality strategy, said: “We observed scant discussion through race action plan meetings of the facial recognition rollout even with obvious cross-over with the plan’s concerns.

“These revelations show once again that the pledges to combat discrimination the police has made through the race action plan are not being translated into broader operations. Our reports have cautioned that new technologies are being rolled out in a landscape where ethnic inequalities, weak scrutiny and poor data collection continue to exist.

“All deployment of this technology must meet strict national standards, be subject to external review, and prove it diminishes rather than exacerbates racial disparity.”

Official Statement

A Home Office spokesperson said: “We treat the conclusions of the report with utmost gravity and we have already taken action. A new algorithm has been externally evaluated and acquired, which has demonstrated no measurable discrimination. It will be trialled early next year and will be undergo further assessment.

“The foremost aim is ensuring public safety. This gamechanging technology will assist officers to put criminals and rapists behind bars. There is human involvement in every step of the procedure and no arrest or charge would be taken without trained officers meticulously examining the results.”