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Police forces across the UK effectively campaigned to use a facial recognition system acknowledged as biased against women, youths, and individuals from minority ethnic backgrounds, following complaints that a more accurate version produced fewer potential suspects.

The Technology in Practice

UK forces utilize the police national database (PND) to carry out searches using historical face recognition. This procedure involves comparing a “probe image” of a suspect against a repository of over 19 million mugshots to find potential matches.

Acknowledged Discrimination

The Home Office admitted last week that the technology was flawed. This admission followed a review 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 ministry stated it “took steps on the findings”.

“It prompts the question of whether facial recognition only becomes effective if users tolerate discrimination in race and sex. Operational ease is a weak argument for overriding basic freedoms.”

Known Issue

Internal documents reveal that this discriminatory flaw has been known about for more than a year. Furthermore, law enforcement argued to overturn an earlier ruling that was designed to address the problem.

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

A Reversed Decision

In reaction, the national police leadership body ordered that the confidence threshold required for potential matches be increased to a level where the disparity was significantly reduced.

However, this decision was reversed the following month following complaints from police that the modified technology was generating fewer “investigative leads”. Internal records show the higher threshold reduced the proportion of queries 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 recent NPL study discovered the system could generate false positives for Black women nearly a hundred times more often than for white 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 incorrectly include some demographic groups in its search results.”

Operational Effectiveness vs. Bias

Outlining the effect of the temporary raise to the system's accuracy setting, the NPCC documents note: “The change greatly lessens the effect of bias across legally safeguarded attributes of ethnicity, generation and sex but had a significant negative impact on operational effectiveness”. The documents add that forces complained that “a once effective tactic now delivered outcomes of questionable value”.

Wider Implementation Proposals

Meanwhile, the government has opened a ten-week consultation on its proposals to expand the use of biometric scanning systems. Policing minister Sarah Jones has described the tool as the “biggest breakthrough since genetic fingerprinting”.

Criticism from Advisors and Monitors

Abimbola Johnson, chair of the independent scrutiny and oversight board for the police race action plan, commented: “There was very little consideration in race action plan meetings of the facial recognition rollout despite clear relevance with the strategy's goals.

“This disclosure show yet again that the anti-racism commitments policing has made via the race action plan are not being translated into wider practice. Our reports have warned that new technologies are being rolled out in a context where ethnic inequalities, inadequate oversight and faulty information gathering continue to exist.

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

Official Statement

A government representative said: “We takes the findings of the study with utmost gravity and we have already taken action. A new algorithm has been independently tested and procured, which has no statistically significant bias. It will be trialled in the coming months and will be undergo evaluation.

“Our priority is protecting the public. This revolutionary tool will assist officers to apprehend and prosecute offenders. There is officer review in each stage of the procedure and no further action would be pursued without specialist personnel meticulously examining the output.”