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Law enforcement agencies across the United Kingdom successfully lobbied to deploy a facial recognition system known to be biased against women, young people, and individuals from minority ethnic backgrounds, after complaining that a more accurate version produced fewer potential suspects.

How the System Works

British police use the police national database (PND) to carry out retrospective facial recognition searches. This procedure entails comparing a “probe image” of a suspect against a database of over 19 million custody photos to find possible hits.

Acknowledged Discrimination

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

“This raises the issue of whether this technology only becomes effective if users tolerate biases in race and gender. Operational ease is a poor argument for overriding basic freedoms.”

Known Issue

Internal documents reveal that this discriminatory flaw has been recognized for over twelve months. Furthermore, law enforcement lobbied to reverse an earlier ruling that was intended to mitigate the problem.

Senior officers were notified of the algorithmic discrimination in late 2024. The government-ordered laboratory study found the system was more likely to suggest incorrect matches for photos of females, Black people, and those under 40 years old.

A Reversed Decision

In response, the National Police Chiefs’ Council (NPCC) ordered that the confidence threshold required for potential matches be increased to a point where the disparity was greatly diminished.

However, this directive was reversed the following month after forces complained that the adjusted system was generating a lower number of “useful lines of inquiry”. Internal records show the stricter setting cut the proportion of searches resulting in possible identifications from over half to a just 14%.

Severe Disparities

Although the authorities refused to say what threshold is currently used, the recent independent review discovered the system could produce false positives for Black women nearly a hundred times more frequently than for Caucasian women at specific configurations.

The Home Office stated on these findings: “The testing identified that in a limited set of circumstances the algorithm is has a greater tendency to incorrectly include some demographic groups in its search results.”

Balancing Utility and Fairness

Outlining the impact of the temporary raise to the system's accuracy setting, the NPCC documents note: “This adjustment greatly lessens the impact of discrimination across protected characteristics of ethnicity, age and sex but had a substantially detrimental effect on operational effectiveness”. The documents further note that forces complained that “a once effective tactic returned results of questionable value”.

Broader Rollout Plans

Meanwhile, the government has opened a two-and-a-half-month public review on its proposals to expand the use of biometric scanning systems. The minister for police the relevant minister has labeled the technology as the “biggest breakthrough since genetic fingerprinting”.

Expert and Oversight Concerns

The chair of a police oversight board, chair of the independent scrutiny and oversight board for the national policing equality strategy, commented: “There was very little discussion in equality strategy sessions of the facial recognition rollout despite clear relevance with the plan’s concerns.

“These revelations show yet again that the pledges to combat discrimination the police has undertaken through the race action plan are failing to be integrated into broader operations. Independent assessments have cautioned that new technologies are being rolled out in a landscape where racial disparities, inadequate oversight and poor data collection already persist.

“Any use of facial recognition must adhere to rigorous official guidelines, be subject to external review, and prove it reduces rather than compounds ethnic bias.”

Official Statement

A Home Office spokesperson stated: “We takes the conclusions of the report with utmost gravity and we have implemented changes. A updated software has been independently tested and acquired, which has demonstrated no measurable discrimination. It will be tested early next year and will be undergo evaluation.

“The foremost aim is ensuring public safety. This gamechanging technology will assist officers to apprehend and prosecute offenders. There is human involvement in each stage of the process and no arrest or charge would be taken without trained officers meticulously examining the output.”