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Law enforcement agencies across the United Kingdom effectively campaigned to deploy a face scanning system acknowledged as biased against women, youths, and individuals from minority ethnic backgrounds, following complaints that a less biased version produced a reduced number of investigative leads.

How the System Works

UK forces use the national police database to conduct searches using historical face recognition. This process entails matching a reference photograph of a person of interest against a repository of over 19 million mugshots to identify possible hits.

Admitted Bias

The UK interior ministry conceded last week that the technology was flawed. This admission came after a study by the government's National Physical Laboratory determined it incorrectly matched people of Black and Asian heritage and women at significantly higher rates than Caucasian males. The ministry said it “took steps on the findings”.

“This raises the issue of whether facial recognition only becomes effective if users accept biases in ethnicity and sex. Operational ease is a poor argument for disregarding basic freedoms.”

Long-Standing Problem

Internal documents reveal that this bias has been recognized for over twelve months. Furthermore, police forces argued to overturn an initial decision that was designed to mitigate the problem.

Police bosses were notified of the system's bias in September 2024. The Home Office-commissioned NPL review concluded the system was more likely to produce incorrect matches for photos of women, Black people, and those aged 40 and under.

A Reversed Decision

In response, the national police leadership body mandated that the confidence threshold required for potential matches be raised to a point where the disparity was greatly diminished.

However, this decision was overturned the next month after forces complained that the modified technology was generating fewer “investigative leads”. NPCC documents show the stricter setting reduced the number of searches that yielded potential matches from over half to a mere 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 incorrect matches for women of Black heritage almost 100 times more often than for white women at certain settings.

The Home Office commented on these results: “Our evaluation found that in a specific scenarios the algorithm is has a greater tendency to incorrectly include some population segments in its match reports.”

Balancing Utility and Fairness

Outlining the effect of the temporary raise to the system's accuracy setting, the police records note: “The change greatly lessens the impact of discrimination across legally safeguarded attributes of ethnicity, age and gender but had a significant negative impact on police efficiency”. The papers add that forces argued 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 plans to expand the use of biometric scanning systems. The minister for police the relevant minister has described the technology as the “biggest breakthrough since genetic fingerprinting”.

Criticism from Advisors and Monitors

Abimbola Johnson, head of the independent scrutiny and oversight board for the national policing equality strategy, commented: “There was very little consideration in equality strategy sessions of the facial recognition rollout despite clear relevance with the strategy's goals.

“These revelations show yet again that the pledges to combat discrimination the police has undertaken through the race action plan are failing to be integrated into broader operations. Our reports have warned that new technologies are being rolled out in a context where racial disparities, weak scrutiny and poor data collection continue to exist.

“Any use of this technology must meet rigorous official guidelines, be independently scrutinised, and demonstrate it diminishes rather than compounds racial disparity.”

Home Office Response

A government representative said: “We treat the findings of the study with utmost gravity and we have implemented changes. A updated software has been externally evaluated and acquired, which has no statistically significant bias. It will be trialled early next year and will be undergo further assessment.

“Our priority is protecting the public. This revolutionary tool will assist police to put criminals and rapists behind bars. There is human involvement in each stage of the process and no further action would be taken without specialist personnel carefully reviewing the results.”