🔗 Share this article

Law enforcement agencies across the UK successfully lobbied to deploy a facial recognition system known to be biased against females, youths, and individuals from minority ethnic backgrounds, after complaining that a more accurate version produced a reduced number of investigative leads.

How the System Works

British police use the national police database to conduct searches using historical face recognition. This procedure involves matching a “probe image” of a person of interest against a repository of more than 19 million custody photos to find possible hits.

Acknowledged Discrimination

The UK interior ministry admitted last week that the technology was flawed. This admission followed a review by the National Physical Laboratory (NPL) determined it misidentified Black and Asian people and women at significantly higher rates than Caucasian males. The ministry said it “took steps on the findings”.

“This raises the question of whether this technology only becomes effective if users tolerate biases in race and gender. Convenience is a weak argument for disregarding fundamental rights.”

Long-Standing Problem

Internal documents show that this bias has been recognized for more than a year. Furthermore, police forces argued to overturn an earlier ruling that was designed to address the problem.

Police bosses were notified of the system's bias in September 2024. The Home Office-commissioned laboratory study found the system was had a higher probability to suggest false positives for photos of females, individuals of Black ethnicity, and those aged 40 and under.

A Policy U-Turn

In reaction, the national police leadership body ordered that the accuracy setting required for possible hits be raised to a level where the bias was greatly diminished.

However, this directive was reversed the following month after forces complained that the adjusted system was producing fewer “investigative leads”. NPCC documents show the stricter setting cut the proportion of searches resulting in potential matches from over half to a just under 15%.

Severe Disparities

Although the authorities refused to say what setting is currently used, the latest NPL study discovered the system could generate incorrect matches for Black women nearly a hundred times more frequently than for white women at certain settings.

The ministry stated on these findings: “The testing found that in a limited set of circumstances the algorithm is more likely to incorrectly include some population segments in its match reports.”

Balancing Utility and Fairness

Outlining the impact of the temporary raise to the system's confidence threshold, the police records state: “This adjustment significantly reduces the effect of bias across legally safeguarded attributes of ethnicity, generation and sex but had a substantially detrimental effect on operational effectiveness”. The documents add 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 proposals to expand the use of facial recognition technology. Policing minister the relevant minister has described the tool as the “most significant advance since DNA matching”.

Criticism from Advisors and Monitors

Abimbola Johnson, chair of the independent scrutiny and oversight board for the national policing equality strategy, said: “We observed very little discussion through race action plan meetings of the technology deployment even with clear relevance with the strategy's goals.

“This disclosure demonstrate yet again that the anti-racism commitments the police has undertaken via the equality initiative 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 faulty information gathering already persist.

“All deployment of facial recognition must meet rigorous official guidelines, be independently scrutinised, and demonstrate it reduces rather than compounds racial disparity.”

Home Office Response

A Home Office spokesperson stated: “We treat the findings of the study with utmost gravity and we have already taken action. A new algorithm has been externally evaluated and acquired, which has no statistically significant bias. It will be tested in the coming months and will be undergo further assessment.

“Our priority is protecting the public. This gamechanging technology will support officers to apprehend and prosecute offenders. There is human involvement in each stage of the procedure and no arrest or charge would be pursued without specialist personnel meticulously examining the results.”