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Police forces across the United Kingdom successfully lobbied to deploy a facial recognition system acknowledged as biased against women, young people, and members of ethnic minority groups, following complaints that a less biased version generated fewer potential suspects.

The Technology in Practice

British police utilize the police national database (PND) to carry out searches using historical face recognition. This procedure involves comparing a reference photograph of a suspect against a repository of over 19 million mugshots to identify potential matches.

Admitted Bias

The Home Office conceded last week that the system was biased. This acknowledgment followed a study by the government's National Physical Laboratory found it misidentified people of Black and Asian heritage and females at significantly higher rates than Caucasian males. The Home Office stated 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. Convenience is a poor argument for overriding basic freedoms.”

Known Issue

Internal documents show that this bias has been known about for more than a year. Furthermore, law enforcement argued to overturn an earlier ruling that was intended to address the problem.

Police bosses were informed of the algorithmic discrimination in September 2024. The government-ordered laboratory study found the system was more likely to suggest false positives for photos of women, individuals of Black ethnicity, and those under 40 years old.

A Policy U-Turn

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

However, this directive was reversed the next month following complaints from police that the modified technology was generating a lower number of “useful lines of inquiry”. Internal records indicate the higher threshold reduced the proportion of searches that yielded possible identifications from over half to a mere 14%.

Severe Disparities

Although the authorities declined to specify what threshold is currently used, the recent independent review discovered the system could generate false positives for women of Black heritage nearly a hundred times more often than for Caucasian women at specific configurations.

The Home Office commented on these results: “Our evaluation found that in a specific scenarios the software is has a greater tendency to incorrectly include some population segments in its match reports.”

Balancing Utility and Fairness

Outlining the effect of the brief increase to the system's accuracy setting, the NPCC documents note: “The change greatly lessens the effect of bias across legally safeguarded attributes of ethnicity, generation and gender but had a significant negative impact on police efficiency”. The documents add that police units argued that “a previously useful tool now delivered results of limited benefit”.

Broader Rollout Plans

Meanwhile, the UK administration has launched a two-and-a-half-month public review on its plans to widen the use of biometric scanning systems. Policing minister Sarah Jones has labeled the technology 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 national policing equality strategy, said: “There was very little consideration through 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 policing has made through the race action plan are not being translated into broader operations. Independent assessments have cautioned that new technologies are being implemented in a landscape where racial disparities, inadequate oversight and faulty information gathering continue to exist.

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

Home Office Response

A Home Office spokesperson said: “We treat the findings of the report with utmost gravity and we have implemented changes. A updated software has been externally evaluated and acquired, which has demonstrated no measurable discrimination. It will be trialled in the coming months and will be undergo further assessment.

“The foremost aim is protecting the public. This gamechanging technology will assist police to apprehend and prosecute offenders. There is human involvement in each stage of the procedure and no further action would be pursued without specialist personnel carefully reviewing the results.”