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Police forces across the United Kingdom effectively campaigned to use a face scanning system acknowledged as biased against women, young people, and individuals from minority ethnic backgrounds, after complaining that a more accurate version produced fewer investigative leads.

The Technology in Practice

UK forces use the police national database (PND) to carry out searches using historical face recognition. This procedure entails comparing a “probe image” of a person of interest against a repository of over 19 million custody photos to find potential matches.

Acknowledged Discrimination

The Home Office admitted last week that the system was flawed. This admission followed a study by the government's National Physical Laboratory determined it incorrectly matched Black and Asian people and females at significantly higher rates than white men. The Home Office said it “had acted on the findings”.

“It prompts the question of whether facial recognition only becomes useful if users accept discrimination in race and sex. Operational ease is a poor argument for disregarding basic freedoms.”

Long-Standing Problem

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

Police bosses were notified of the algorithmic discrimination in September 2024. The Home Office-commissioned NPL review found the system was more likely to produce incorrect matches for photos of females, individuals of Black ethnicity, and those under 40 years old.

A Policy U-Turn

In response, the National Police Chiefs’ Council (NPCC) ordered that the confidence threshold required for potential matches be raised to a level where the disparity was significantly reduced.

However, this directive was overturned the following month following complaints from police that the modified technology was producing a lower number of “useful lines of inquiry”. NPCC documents indicate the higher threshold cut the number of searches resulting in potential matches from 56% to a just under 15%.

Profound Inequalities

Although the Home Office and NPCC refused to say what setting is now in operation, the recent NPL study discovered the system could produce false positives for women of Black heritage almost 100 times more frequently than for Caucasian women at certain settings.

The Home Office commented on these findings: “The testing identified that in a limited set of circumstances the software is more likely to wrongly flag some demographic groups in its search results.”

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 discrimination across protected characteristics of ethnicity, generation and sex but had a significant negative impact on police efficiency”. The papers further note that police units complained that “a once effective tactic now delivered results of limited benefit”.

Broader Rollout Plans

Meanwhile, the government has opened a two-and-a-half-month public review on its plans to widen the use of facial recognition technology. The minister for police Sarah Jones has labeled the tool as the “most significant advance since genetic fingerprinting”.

Criticism from Advisors and Monitors

The chair of a police oversight board, chair of the advisory panel for the police race action plan, commented: “There was very little consideration through equality strategy sessions of the technology deployment despite clear relevance with the strategy's goals.

“These revelations show yet again that the anti-racism commitments policing has made through the equality initiative are not being translated into wider practice. Our reports have cautioned that new technologies are being rolled out in a landscape where racial disparities, inadequate oversight and poor data collection already persist.

“Any use of facial recognition must adhere to strict national standards, be subject to external review, and demonstrate it diminishes rather than exacerbates racial disparity.”

Official Statement

A government representative stated: “The Home Office takes the conclusions of the study seriously and we have already taken action. A updated software has been independently tested and acquired, which has no statistically significant bias. It will be tested in the coming months and will be subject to evaluation.

“Our priority is ensuring public safety. This revolutionary tool will assist police to put criminals and rapists behind bars. There is officer review in every step of the process and no further action would be taken without trained officers carefully reviewing the output.”