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Law enforcement agencies across the United Kingdom effectively campaigned to deploy a facial recognition system known to be biased against females, young people, and individuals from ethnic minority groups, after complaining that a more accurate version generated fewer investigative leads.

How the System Works

UK forces utilize the police national database (PND) to carry out searches using historical face recognition. This process entails matching a “probe image” of a suspect against a repository of more than 19 million custody photos to find possible hits.

Acknowledged Discrimination

The Home Office admitted last week that the system was biased. This acknowledgment followed a study by the National Physical Laboratory (NPL) determined it incorrectly matched people of Black and Asian heritage and females at much greater frequency than white men. The ministry said it “had acted on the findings”.

“This raises the question of whether this technology only becomes useful if users tolerate biases in race and sex. Convenience is a poor argument for overriding fundamental rights.”

Long-Standing Problem

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

Senior officers were informed of the algorithmic discrimination in late 2024. The Home Office-commissioned NPL review found the system was more likely to suggest false positives for photos of females, Black people, and those under 40 years old.

A Policy U-Turn

In reaction, the national police leadership body ordered that the accuracy setting required for potential matches be raised to a level where the bias was significantly reduced.

However, this directive was overturned the following month after forces complained that the modified technology was producing fewer “investigative leads”. NPCC documents indicate the higher threshold cut the proportion of searches resulting in possible identifications from 56% to a mere under 15%.

Profound Inequalities

Although the Home Office and NPCC declined to specify what threshold is currently used, the latest NPL study discovered the system could generate incorrect matches for women of Black heritage almost 100 times more often than for white women at specific configurations.

The ministry stated on these findings: “The testing identified that in a limited set of circumstances the software is has a greater tendency to incorrectly include some demographic groups in its match reports.”

Operational Effectiveness vs. Bias

Describing the impact of the brief increase to the system's confidence threshold, the NPCC documents note: “The change significantly reduces the effect of bias across legally safeguarded attributes of ethnicity, generation and sex but had a substantially detrimental effect on operational effectiveness”. The papers add that forces complained that “a previously useful tool returned outcomes of limited benefit”.

Wider Implementation Proposals

Meanwhile, the UK administration has launched a two-and-a-half-month consultation on its proposals to expand the use of facial recognition technology. Policing minister Sarah Jones has described the technology as the “most significant advance since DNA matching”.

Criticism from Advisors and Monitors

The chair of a police oversight board, head of the advisory panel for the national policing equality strategy, said: “We observed very little discussion in race action plan meetings of the technology deployment despite clear relevance with the strategy's goals.

“These revelations show once again that the pledges to combat discrimination the police has made via the equality initiative are failing to be integrated into broader operations. Our reports have warned that new technologies are being implemented in a landscape where racial disparities, inadequate oversight and poor data collection already persist.

“Any use of this technology must adhere to strict national standards, be subject to external review, and prove it reduces rather than exacerbates ethnic bias.”

Official Statement

A government representative said: “The Home Office treat the findings of the report seriously and we have implemented changes. A new algorithm has been independently tested and procured, which has no statistically significant bias. It will be tested early next year and will be undergo further assessment.

“Our priority is ensuring public safety. This gamechanging technology will support officers to apprehend and prosecute offenders. There is officer review in every step of the procedure and no arrest or charge would be taken without trained officers meticulously examining the output.”