🔗 Share this article

Law enforcement agencies across the United Kingdom effectively campaigned to deploy a face scanning system acknowledged as biased against women, young people, and members of minority ethnic backgrounds, following complaints that a less biased version produced fewer potential suspects.

The Technology in Practice

UK forces utilize the national police database to conduct retrospective facial recognition searches. This process entails comparing a reference photograph of a suspect against a database of more than 19 million mugshots to find potential matches.

Admitted Bias

The UK interior ministry conceded last week that the system was biased. This admission followed a review by the National Physical Laboratory (NPL) found it misidentified Black and Asian people and females at significantly higher rates than white men. The ministry stated it “had acted on the findings”.

“This raises the issue of whether facial recognition only becomes useful if users tolerate discrimination in ethnicity and sex. Operational ease is a poor argument for disregarding fundamental rights.”

Long-Standing Problem

Internal documents show that this bias has been known about for more than a year. Furthermore, law enforcement lobbied to reverse an initial decision that was designed to address the problem.

Police bosses were notified of the system's bias in late 2024. The government-ordered NPL review concluded the system was had a higher probability to suggest 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 bias was significantly reduced.

However, this directive was overturned the following month following complaints from police that the adjusted system was generating a lower number of “investigative leads”. NPCC documents show the higher threshold cut the number of searches resulting in possible identifications from 56% to a just 14%.

Profound Inequalities

Although the Home Office and NPCC declined to specify what threshold is currently used, the recent NPL study found the system could generate false positives for Black women nearly a hundred times more often than for white women at specific configurations.

The Home Office stated on these findings: “Our evaluation found that in a specific scenarios the software is more likely to incorrectly include some population segments in its search results.”

Operational Effectiveness vs. Bias

Describing the effect of the brief increase to the system's confidence threshold, the NPCC documents state: “The change significantly reduces the impact of discrimination across legally safeguarded attributes of race, age and sex but had a significant negative impact on operational effectiveness”. The papers add that forces argued that “a previously useful tool now delivered outcomes of limited benefit”.

Wider Implementation Proposals

Meanwhile, the government has opened a two-and-a-half-month public review on its plans to expand the use of facial recognition technology. The minister for police Sarah Jones has labeled the technology as the “most significant advance since genetic fingerprinting”.

Criticism from Advisors and Monitors

The chair of a police oversight board, chair of the independent scrutiny and oversight board for the national policing equality strategy, commented: “We observed very little discussion in equality strategy sessions of the technology deployment even with clear relevance with the strategy's goals.

“This disclosure demonstrate once again that the pledges to combat discrimination policing has made via the race action plan are failing to be integrated into broader operations. Independent assessments have cautioned that innovative tools are being rolled out in a context where ethnic inequalities, inadequate oversight and poor data collection already persist.

“Any use of this technology must meet strict national standards, be independently scrutinised, and prove it reduces rather than compounds ethnic bias.”

Official Statement

A government representative stated: “We treat the findings of the report 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 tested early next year and will be undergo further assessment.

“The foremost aim is ensuring public safety. This revolutionary tool will support police to put criminals and rapists behind bars. There is officer review in each stage of the process and no arrest or charge would be taken without trained officers carefully reviewing the results.”