British Law Enforcement Agencies Campaign to Employ Discriminatory Face Scanning Systems

Police forces across the United Kingdom successfully lobbied to deploy a face scanning system known to be discriminatory against women, youths, and members of minority ethnic backgrounds, following complaints that a less biased version produced fewer potential suspects.

The Technology in Practice

UK forces use the police national database (PND) to carry out retrospective facial recognition searches. This process involves matching a “probe image” of a person of interest against a database of more than 19 million custody photos to identify possible hits.

Admitted Bias

The UK interior ministry admitted last week that the technology was flawed. This admission followed a review by the government's National Physical Laboratory found it incorrectly matched Black and Asian people and females at significantly higher rates than Caucasian males. The Home Office said it “took steps on the findings”.

“This raises the issue of whether facial recognition only becomes effective if users accept biases in race and sex. Convenience is a weak argument for overriding fundamental rights.”

Long-Standing Problem

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

Police bosses were informed of the system's bias in late 2024. The Home Office-commissioned laboratory study found the system was more likely to produce false positives for photos of women, Black people, and those aged 40 and under.

A Reversed Decision

In response, the National Police Chiefs’ Council (NPCC) ordered that the accuracy setting required for possible hits be increased to a point where the disparity was significantly reduced.

However, this decision was overturned the following month after forces complained that the modified technology was producing fewer “useful lines of inquiry”. Internal records show the higher threshold cut the number of searches resulting in possible identifications from over half to a just under 15%.

Profound Inequalities

Although the Home Office and NPCC refused to say what setting is currently used, the recent NPL study discovered the system could produce incorrect matches for women of Black heritage nearly a hundred times more frequently than for Caucasian women at certain settings.

The Home Office stated on these results: “The testing identified that in a specific scenarios the algorithm is has a greater tendency to wrongly flag some population segments in its search results.”

Balancing Utility and Fairness

Outlining the effect of the brief increase to the system's accuracy setting, the NPCC documents state: “The change greatly lessens the effect of bias across legally safeguarded attributes of race, age and sex but had a substantially detrimental effect on operational effectiveness”. The papers add that police units argued that “a once effective tactic now delivered results of questionable value”.

Wider Implementation Proposals

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

Expert and Oversight Concerns

Abimbola Johnson, head of the independent scrutiny and oversight board for the police race action plan, said: “We observed scant consideration through race action plan meetings of the technology deployment despite obvious cross-over with the strategy's goals.

“This disclosure demonstrate once again that the anti-racism commitments policing has undertaken through the equality initiative are failing to be integrated into broader operations. Independent assessments have warned that new technologies are being rolled out in a context where ethnic inequalities, weak scrutiny and poor data collection continue to exist.

“All deployment of this technology must meet rigorous official guidelines, be subject to external review, and demonstrate it reduces rather than exacerbates racial disparity.”

Home Office Response

A government representative stated: “The Home Office takes the conclusions of the study seriously 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 subject to further assessment.

“The foremost aim is protecting the public. This gamechanging technology will support police to apprehend and prosecute offenders. There is human involvement in every step of the process and no further action would be pursued without specialist personnel carefully reviewing the results.”