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Police forces across the UK successfully lobbied to use a face scanning system known to be discriminatory against females, young people, and individuals from minority ethnic backgrounds, after complaining that a more accurate version generated a reduced number of investigative leads.

The Technology in Practice

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

Admitted Bias

The UK interior ministry admitted last week that the technology was biased. This acknowledgment came after a review 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 Home Office said it “had acted on the findings”.

“This raises the question of whether facial recognition only becomes useful if users tolerate biases in ethnicity and gender. Convenience is a poor argument for overriding basic freedoms.”

Long-Standing Problem

Official papers show that this bias has been known about for more than a year. Furthermore, police forces lobbied to reverse an initial decision that was intended to address the problem.

Senior officers were informed of the system's bias in late 2024. The government-ordered NPL review found the system was more likely to produce false positives for images depicting women, Black people, and those aged 40 and under.

A Reversed Decision

In reaction, the national police leadership body mandated that the confidence threshold required for potential matches be raised to a point where the bias was significantly reduced.

However, this directive was overturned the following month following complaints from police that the adjusted system was producing a lower number of “investigative leads”. NPCC documents show the higher threshold cut the number of searches resulting in possible identifications from 56% to a just 14%.

Severe Disparities

Although the Home Office and NPCC refused to say what setting is now in operation, the latest independent review discovered the system could produce incorrect matches for Black women nearly a hundred times more often than for white women at specific configurations.

The Home Office stated on these results: “The testing found that in a limited set of circumstances the algorithm is more likely to incorrectly include some demographic groups in its search results.”

Operational Effectiveness vs. Bias

Outlining the impact of the temporary raise to the system's accuracy setting, the NPCC documents state: “The change significantly reduces the impact of bias across protected characteristics of race, age and sex but had a significant negative impact on operational effectiveness”. The documents further note that police units complained that “a previously useful tool returned outcomes of questionable value”.

Broader Rollout Plans

Meanwhile, the government has launched a ten-week public review on its plans to expand the use of facial recognition technology. Policing minister the relevant minister has described the tool as the “biggest breakthrough since genetic fingerprinting”.

Expert and Oversight Concerns

The chair of a police oversight board, head of the advisory panel for the police race action plan, commented: “We observed very little discussion in race action plan meetings of the facial recognition rollout despite clear relevance with the plan’s concerns.

“This disclosure show once again that the anti-racism commitments the police has undertaken through the equality initiative are failing to be integrated into wider practice. Our reports have warned that new technologies are being rolled out in a context where ethnic inequalities, inadequate oversight and poor data collection already persist.

“All deployment of facial recognition must meet strict national standards, be subject to external review, and prove it diminishes rather than exacerbates racial disparity.”

Official Statement

A government representative said: “We takes the findings of the study seriously and we have implemented changes. A new algorithm has been externally evaluated and procured, which has no statistically significant bias. It will be tested early next year and will be undergo evaluation.

“The foremost aim is protecting the public. This revolutionary tool will assist 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 pursued without trained officers meticulously examining the output.”