British Law Enforcement Agencies Lobbied to Employ Biased Face Scanning Technology

Law enforcement agencies across the United Kingdom successfully lobbied to deploy a facial recognition system acknowledged as discriminatory against females, young people, and members of minority ethnic backgrounds, following complaints that a more accurate version generated a reduced number of potential suspects.

The Technology in Practice

British police use the police national database (PND) to carry out searches using historical face recognition. This process involves matching a “probe image” of a person of interest against a repository of over 19 million mugshots to find possible hits.

Acknowledged Discrimination

The UK interior ministry admitted last week that the technology was biased. This acknowledgment followed a study by the government's National Physical Laboratory determined it misidentified people of Black and Asian heritage and females at significantly higher rates than Caucasian males. The Home Office said it “took steps on the findings”.

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

Long-Standing Problem

Official papers show that this discriminatory flaw has been known about for more than a year. Furthermore, police forces argued to overturn an earlier ruling that was designed to address the problem.

Senior officers were notified of the algorithmic discrimination in September 2024. The Home Office-commissioned NPL review found the system was had a higher probability to produce false positives for images depicting women, Black people, and those aged 40 and under.

A Reversed Decision

In reaction, the National Police Chiefs’ Council (NPCC) ordered that the accuracy setting required for possible hits be raised to a point where the bias was greatly diminished.

However, this directive was reversed the next month after forces complained that the modified technology was producing a lower number of “useful lines of inquiry”. Internal records indicate the higher threshold reduced the number of queries that yielded potential matches from over half to a just 14%.

Severe Disparities

Although the Home Office and NPCC declined to specify what threshold is currently used, the latest independent review found 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 findings: “The testing identified that in a limited set of circumstances the algorithm is more likely to incorrectly include some demographic groups in its search results.”

Balancing Utility and Fairness

Outlining the effect of the brief increase to the system's accuracy setting, the NPCC documents note: “This adjustment significantly reduces the impact of bias across legally safeguarded attributes of race, age and sex but had a substantially detrimental effect on police efficiency”. The documents further note that forces argued that “a once effective tactic now delivered results of questionable value”.

Broader Rollout Plans

Meanwhile, the government has opened a ten-week public review on its proposals to expand the use of biometric scanning systems. The minister for police the relevant minister has described the tool as the “biggest breakthrough since DNA matching”.

Expert and Oversight Concerns

Abimbola Johnson, head of the independent scrutiny and oversight board for the police race action plan, commented: “We observed scant consideration in race action plan meetings of the technology deployment despite obvious cross-over with the plan’s concerns.

“This disclosure demonstrate yet again that the anti-racism commitments the police has made via the race action plan are failing to be integrated into broader operations. Independent assessments have warned that new technologies are being rolled out in a context where racial disparities, weak scrutiny and faulty information gathering already persist.

“Any use of this technology must adhere to rigorous official guidelines, be independently scrutinised, and prove it reduces rather than compounds racial disparity.”

Official Statement

A Home Office spokesperson stated: “The Home Office treat the conclusions of the study seriously and we have already taken action. A updated software has been externally evaluated and procured, 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 gamechanging technology 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 specialist personnel carefully reviewing the results.”