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Police forces across the United Kingdom effectively campaigned to use a facial recognition system known to be discriminatory against females, young people, and individuals from minority ethnic backgrounds, following complaints that a more accurate version generated fewer potential suspects.

How the System Works

British police utilize the police national database (PND) to conduct searches using historical face recognition. This procedure involves comparing a reference photograph of a suspect against a database of over 19 million custody photos to identify possible hits.

Admitted Bias

The Home Office conceded last week that the technology was biased. This admission came after a review by the National Physical Laboratory (NPL) determined it misidentified people of Black and Asian heritage and females at significantly higher rates than white men. The Home Office stated it “had acted on the findings”.

“It prompts the question of whether this technology only becomes useful if users accept biases in ethnicity and gender. Convenience is a poor argument for overriding fundamental rights.”

Long-Standing Problem

Internal documents reveal that this bias has been known about for over twelve months. Furthermore, law enforcement lobbied to reverse an earlier ruling that was intended to address the problem.

Police bosses were informed of the system's bias in late 2024. The Home Office-commissioned NPL review found the system was had a higher probability to suggest false positives for images depicting females, Black people, and those under 40 years old.

A Reversed Decision

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 significantly reduced.

However, this decision was reversed the following month after forces complained that the modified technology was producing a lower number of “investigative leads”. NPCC documents show the higher threshold reduced the proportion of searches resulting in possible identifications from over half to a just under 15%.

Profound Inequalities

Although the authorities declined to specify what threshold is currently used, the latest independent review found the system could generate false positives for Black women almost 100 times more frequently than for Caucasian women at specific configurations.

The ministry stated on these results: “The testing found that in a limited set of circumstances the software is more likely to wrongly flag some demographic groups in its match reports.”

Balancing Utility and Fairness

Describing the impact of the temporary raise to the system's accuracy setting, the NPCC documents state: “This adjustment greatly lessens the impact of discrimination across protected characteristics of race, age and sex but had a substantially detrimental effect on operational effectiveness”. The documents further note that police units complained that “a once effective tactic now delivered results of limited benefit”.

Broader Rollout Plans

Meanwhile, the government has launched a two-and-a-half-month public review on its proposals to widen the use of biometric scanning systems. Policing minister the relevant minister has labeled the technology as the “most significant advance since DNA matching”.

Criticism from Advisors and Monitors

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 facial recognition rollout despite clear relevance with the strategy's goals.

“This disclosure show once again that the pledges to combat discrimination policing has undertaken through the equality initiative are not being translated into broader operations. Independent assessments have cautioned that innovative tools are being rolled out in a context where racial disparities, inadequate oversight and poor data collection continue to exist.

“Any use of facial recognition must meet strict national standards, be independently scrutinised, and prove it diminishes rather than compounds racial disparity.”

Home Office Response

A Home Office spokesperson stated: “The Home Office takes the conclusions of the study 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 revolutionary tool will support officers to put criminals and rapists behind bars. There is human involvement in each stage of the procedure and no arrest or charge would be taken without trained officers meticulously examining the results.”