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Police forces across the United Kingdom effectively campaigned to use a facial recognition system acknowledged as discriminatory against women, youths, and members of ethnic minority groups, following complaints that a more accurate version produced fewer potential suspects.

The Technology in Practice

UK forces use the police national database (PND) to conduct retrospective facial recognition searches. This procedure entails comparing a reference photograph of a suspect against a database of more than 19 million custody photos to find potential matches.

Acknowledged Discrimination

The Home Office conceded last week that the system was biased. This acknowledgment came after a review by the National Physical Laboratory (NPL) determined it incorrectly matched people of Black and Asian heritage and women at significantly higher rates than white men. The ministry said it “took steps on the findings”.

“This raises the issue of whether facial recognition only becomes useful if users tolerate biases in race and sex. Operational ease is a poor argument for overriding basic freedoms.”

Known Issue

Internal documents reveal that this discriminatory flaw has been recognized for more than a year. Furthermore, police forces argued to overturn an earlier ruling that was intended to address the problem.

Senior officers were notified of the algorithmic discrimination in September 2024. The Home Office-commissioned laboratory study found the system was had a higher probability 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 potential matches be raised to a point where the bias was significantly reduced.

However, this directive was reversed the following month following complaints from police that the adjusted system was producing a lower number of “investigative leads”. Internal records show the stricter setting reduced the proportion of queries resulting in possible identifications from 56% to a just under 15%.

Severe Disparities

Although the Home Office and NPCC declined to specify what setting is now in operation, the recent independent review found the system could generate false positives for Black women almost 100 times more often than for white women at certain settings.

The ministry commented on these results: “Our evaluation identified that in a limited set of circumstances the algorithm is has a greater tendency to incorrectly include some population segments in its match reports.”

Balancing Utility and Fairness

Outlining the effect of the temporary raise to the system's accuracy setting, the police records note: “This adjustment significantly reduces the effect of discrimination across legally safeguarded attributes of race, age and sex but had a substantially detrimental effect on operational effectiveness”. The papers add that forces complained that “a once effective tactic now delivered outcomes of questionable value”.

Broader Rollout Plans

Meanwhile, the government has launched a two-and-a-half-month public review on its proposals to expand the use of facial recognition technology. Policing minister the relevant minister has described the tool as the “biggest breakthrough since DNA matching”.

Criticism from Advisors and Monitors

The chair of a police oversight board, chair of the independent scrutiny and oversight board for the national policing equality strategy, said: “We observed very little discussion in equality strategy sessions of the facial recognition rollout despite obvious cross-over with the plan’s concerns.

“These revelations show once again that the pledges to combat discrimination the police has undertaken via the race action plan are not being translated into wider practice. Our reports have warned that innovative tools are being rolled out in a context where racial disparities, inadequate oversight and poor data collection already persist.

“Any use of this technology must meet rigorous official guidelines, be independently scrutinised, and prove it reduces rather than compounds racial disparity.”

Home Office Response

A Home Office spokesperson said: “The Home Office treat the findings of the report with utmost gravity and we have implemented changes. A new algorithm has been externally evaluated and procured, which has demonstrated no measurable discrimination. It will be tested in the coming months and will be undergo evaluation.

“The foremost aim is ensuring public safety. This gamechanging technology will support officers to put criminals and rapists behind bars. There is human involvement in every step of the process and no further action would be pursued without specialist personnel meticulously examining the results.”