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Police forces across the UK effectively campaigned to use a face scanning system known to be biased against females, young people, and individuals from ethnic minority groups, following complaints that a more accurate version generated fewer potential suspects.

The Technology in Practice

UK forces use the police national database (PND) to carry out searches using historical face recognition. This process involves matching a “probe image” of a suspect against a repository of over 19 million mugshots to identify potential matches.

Acknowledged Discrimination

The Home Office admitted last week that the system was biased. This admission came after a study by the government's National Physical Laboratory determined it incorrectly matched people of Black and Asian heritage and women at significantly higher rates than Caucasian males. The Home Office stated it “took steps on the findings”.

“It prompts the issue of whether facial recognition only becomes effective if users accept discrimination in race and sex. Convenience is a poor argument for overriding basic freedoms.”

Known Issue

Official papers show that this bias has been recognized for over twelve months. Furthermore, law enforcement argued to overturn an initial decision that was intended to address the problem.

Police bosses were notified of the algorithmic discrimination in late 2024. The Home Office-commissioned laboratory study found the system was more likely to produce false positives for photos of women, individuals of Black ethnicity, and those under 40 years old.

A Policy U-Turn

In reaction, the national police leadership body ordered that the confidence threshold required for potential matches be increased to a point where the disparity was greatly diminished.

However, this decision was reversed the following month following complaints from police that the modified technology was generating a lower number of “investigative leads”. NPCC documents indicate the higher threshold cut the proportion of searches resulting in potential matches from 56% to a mere under 15%.

Profound Inequalities

Although the Home Office and NPCC declined to specify what setting is now in operation, the latest independent review found the system could produce incorrect matches for Black women nearly a hundred times more often than for white women at certain settings.

The ministry stated on these findings: “The testing found that in a specific scenarios the algorithm is has a greater tendency to wrongly flag some demographic groups in its search results.”

Balancing Utility and Fairness

Outlining the effect of the brief increase to the system's accuracy setting, the police records state: “The change greatly lessens the effect of bias across protected characteristics of ethnicity, generation and gender but had a substantially detrimental effect on operational effectiveness”. The documents further note that forces argued that “a previously useful tool returned outcomes of limited benefit”.

Broader Rollout Plans

Meanwhile, the UK administration has launched a two-and-a-half-month consultation on its proposals to widen the use of biometric scanning systems. The minister for police the relevant minister 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 advisory panel for the national policing equality strategy, commented: “We observed scant discussion through equality strategy sessions of the facial recognition rollout even with obvious cross-over with the strategy's goals.

“This disclosure demonstrate yet again that the pledges to combat discrimination policing has undertaken through the race action plan are failing to be integrated into wider practice. Independent assessments have cautioned that new technologies are being implemented in a context where racial disparities, inadequate oversight and faulty information gathering continue to exist.

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

Official Statement

A Home Office spokesperson said: “We takes the conclusions of the report seriously and we have implemented changes. A new algorithm has been independently tested and procured, which has demonstrated no measurable discrimination. It will be tested early next year and will be undergo further assessment.

“Our priority is ensuring public safety. This revolutionary tool will assist police to put criminals and rapists behind bars. There is human involvement in each stage of the procedure and no further action would be pursued without trained officers carefully reviewing the output.”