🔗 Share this article

Law enforcement agencies across the UK effectively campaigned to use a facial recognition system known to be biased against females, young people, and members of minority ethnic backgrounds, following complaints that a more accurate version generated fewer investigative leads.

How the System Works

UK forces use the police national database (PND) to carry out retrospective facial recognition searches. This procedure involves matching a “probe image” of a person of interest against a database of more than 19 million mugshots to identify potential matches.

Acknowledged Discrimination

The UK interior ministry conceded last week that the technology was biased. This acknowledgment came after a review by the government's National Physical Laboratory determined it misidentified people of Black and Asian heritage and females at much greater frequency than white men. The ministry said it “had acted on the findings”.

“It prompts the question of whether this technology only becomes effective if users accept biases in ethnicity and sex. Operational ease is a poor argument for disregarding fundamental rights.”

Long-Standing Problem

Internal documents show that this discriminatory flaw has been known about for over twelve months. Furthermore, police forces argued to overturn an earlier ruling that was intended to mitigate the problem.

Police bosses were notified of the system's bias in late 2024. The Home Office-commissioned NPL review found the system was had a higher probability to suggest false positives for images depicting females, Black people, and those under 40 years old.

A Reversed Decision

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

However, this decision was reversed the next month following complaints from police that the modified technology was producing fewer “useful lines of inquiry”. NPCC documents indicate the higher threshold reduced the proportion of queries resulting in possible identifications from over half to a just 14%.

Profound Inequalities

Although the authorities declined to specify what threshold is currently used, the recent independent review discovered the system could generate incorrect matches for Black women nearly a hundred times more often than for Caucasian women at certain settings.

The Home Office stated on these findings: “The testing identified that in a specific scenarios the software is more likely to incorrectly include some population segments in its match reports.”

Operational Effectiveness vs. Bias

Outlining the impact of the brief increase to the system's confidence threshold, the NPCC documents state: “The change significantly reduces the impact of discrimination across protected characteristics of ethnicity, age and sex but had a substantially detrimental effect on police efficiency”. The papers add that police units argued that “a previously useful tool returned outcomes of questionable value”.

Wider Implementation Proposals

Meanwhile, the UK administration has launched a two-and-a-half-month public review on its proposals to expand the use of biometric scanning systems. Policing minister Sarah Jones has described the technology as the “most significant advance since DNA matching”.

Criticism from Advisors and Monitors

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 facial recognition rollout even with obvious cross-over with the plan’s concerns.

“This disclosure demonstrate yet again that the anti-racism commitments policing has made via the race action plan are failing to be integrated into wider practice. Independent assessments have cautioned that innovative tools are being rolled out in a context where racial disparities, inadequate oversight and poor data collection continue to exist.

“All deployment of this technology must adhere to rigorous official guidelines, be subject to external review, and prove it reduces rather than compounds ethnic bias.”

Home Office Response

A government representative said: “We treat the findings of the report seriously and we have implemented changes. A updated software has been externally evaluated and acquired, which has demonstrated no measurable discrimination. 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 process and no arrest or charge would be taken without specialist personnel meticulously examining the output.”