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Law enforcement agencies across the UK effectively campaigned to use a face scanning system acknowledged as biased against women, young people, and members of minority ethnic backgrounds, following complaints that a less biased version produced fewer potential suspects.

How the System Works

British police utilize the police national database (PND) to carry out retrospective facial recognition searches. This process involves matching 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 technology was flawed. This admission came after a review by the government's National Physical Laboratory determined it misidentified Black and Asian people and women at much greater frequency than Caucasian males. The ministry stated it “took steps on the findings”.

“This raises the issue of whether this technology only becomes useful if users tolerate discrimination in race and gender. Operational ease is a poor argument for disregarding fundamental rights.”

Known Issue

Internal documents show that this bias has been known about for over twelve months. Furthermore, police forces argued to overturn an initial decision that was intended to address the problem.

Senior officers were notified of the system's bias in September 2024. The government-ordered laboratory study concluded the system was had a higher probability to produce false positives for images depicting females, individuals of Black ethnicity, and those under 40 years old.

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 point where the disparity was greatly diminished.

However, this decision was overturned the following month following complaints from police that the modified technology was generating fewer “useful lines of inquiry”. NPCC documents show the higher threshold reduced the number of searches that yielded possible identifications from over half to a mere under 15%.

Profound Inequalities

Although the authorities refused to say what setting is currently used, the recent independent review discovered the system could generate false positives for women of Black heritage almost 100 times more frequently than for Caucasian women at specific configurations.

The ministry commented on these results: “The testing found that in a limited set of circumstances the algorithm is more likely to wrongly flag some population segments in its match reports.”

Balancing Utility and Fairness

Describing the effect of the brief increase to the system's accuracy setting, the NPCC documents note: “The change significantly reduces the impact of bias across protected characteristics of ethnicity, generation and sex but had a significant negative impact on police efficiency”. The documents add that forces complained that “a previously useful tool returned outcomes of limited benefit”.

Broader Rollout Plans

Meanwhile, the government has opened a ten-week public review on its plans to widen the use of biometric scanning systems. The minister for police the relevant minister has described the technology as the “most significant advance since DNA matching”.

Expert and Oversight Concerns

The chair of a police oversight board, chair of the independent scrutiny and oversight board for the police race action plan, said: “We observed scant discussion in equality strategy sessions of the technology deployment even with obvious cross-over with the strategy's goals.

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

“Any use of facial recognition must meet rigorous official guidelines, be independently scrutinised, and demonstrate it reduces rather than exacerbates ethnic bias.”

Official Statement

A Home Office spokesperson said: “We treat the findings of the study with utmost gravity and we have implemented changes. A updated software has been independently tested and acquired, which has no statistically significant bias. It will be tested early next year and will be subject to evaluation.

“The foremost aim is protecting the public. This revolutionary tool will assist police to apprehend and prosecute offenders. There is human involvement in every step of the procedure and no arrest or charge would be taken without trained officers carefully reviewing the output.”