🔗 Share this article

Law enforcement agencies across the UK successfully lobbied to deploy a facial recognition system known to be biased against women, young people, and members of minority ethnic backgrounds, following complaints that a less biased version produced a reduced number of potential suspects.

How the System Works

UK forces utilize the national police database to carry out searches using historical face recognition. This process entails matching a reference photograph of a suspect against a repository of over 19 million mugshots to identify potential matches.

Admitted Bias

The UK interior ministry conceded last week that the system was biased. This acknowledgment came after a study by the National Physical Laboratory (NPL) found it misidentified Black and Asian people and women at much greater frequency than white men. The Home Office stated it “had acted on the findings”.

“This raises the question of whether facial recognition only becomes effective if users tolerate discrimination in ethnicity and sex. Operational ease is a poor argument for overriding basic freedoms.”

Known Issue

Official papers show that this bias has been recognized for more than a year. Furthermore, police forces argued to overturn an initial decision that was designed to mitigate the problem.

Senior officers were notified of the system's bias in September 2024. The government-ordered laboratory study found the system was had a higher probability to suggest false positives for photos of women, individuals of Black ethnicity, and those aged 40 and under.

A Reversed Decision

In reaction, the National Police Chiefs’ Council (NPCC) mandated that the confidence threshold required for potential matches be raised to a level where the bias was significantly reduced.

However, this decision was overturned the following month after forces complained that the adjusted system was generating fewer “useful lines of inquiry”. Internal records show the stricter setting reduced the number of queries that yielded potential matches from 56% to a just under 15%.

Severe Disparities

Although the authorities refused to say what threshold is now in operation, the latest NPL study discovered the system could generate false positives for women of Black heritage nearly a hundred times more frequently than for white women at specific configurations.

The ministry stated on these results: “Our evaluation 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

Describing the effect of the temporary raise to the system's confidence threshold, the police records state: “The change significantly reduces the effect of bias across protected characteristics of ethnicity, generation and gender but had a substantially detrimental effect on operational effectiveness”. The papers further note that forces argued that “a once effective tactic now delivered results of questionable value”.

Wider Implementation Proposals

Meanwhile, the government has launched a two-and-a-half-month public review on its proposals to widen the use of biometric scanning systems. Policing minister the relevant minister has described the tool as the “biggest breakthrough since DNA matching”.

Expert and Oversight Concerns

The chair of a police oversight board, head of the independent scrutiny and oversight board for the police race action plan, commented: “We observed very little consideration in equality strategy sessions of the technology deployment even with obvious cross-over with the plan’s concerns.

“These revelations demonstrate once again that the pledges to combat discrimination the police has undertaken through the race action plan are failing to be integrated into wider practice. Our reports have warned that innovative tools are being implemented in a context where ethnic inequalities, inadequate oversight and faulty information gathering continue to exist.

“All deployment of facial recognition must meet strict national standards, be independently scrutinised, and prove it diminishes rather than exacerbates racial disparity.”

Official Statement

A government representative stated: “The Home Office takes the findings of the study seriously and we have implemented changes. A updated software has been externally evaluated and procured, which has demonstrated no measurable discrimination. It will be trialled in the coming months and will be subject to further assessment.

“The foremost aim is ensuring public safety. This revolutionary tool will support officers to apprehend and prosecute offenders. There is human involvement in every step of the procedure and no further action would be taken without specialist personnel meticulously examining the output.”