🔗 Share this article

Law enforcement agencies across the UK effectively campaigned to deploy a facial recognition system acknowledged as biased against females, young people, and individuals from minority ethnic backgrounds, after complaining that a less biased version generated a reduced number of potential suspects.

How the System Works

UK forces utilize the national police database to conduct searches using historical face recognition. This process entails comparing a “probe image” of a suspect against a repository of more than 19 million custody photos to identify possible hits.

Admitted Bias

The UK interior ministry admitted last week that the system was biased. This acknowledgment came after a review by the National Physical Laboratory (NPL) determined it incorrectly matched people of Black and Asian heritage and women at much greater frequency than white men. The ministry said it “took steps on the findings”.

“This raises the issue of whether this technology only becomes effective if users accept discrimination in ethnicity and gender. Convenience is a poor argument for overriding fundamental rights.”

Known Issue

Internal documents reveal that this bias has been recognized for more than a year. Furthermore, law enforcement 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 NPL review found the system was had a higher probability to produce false positives for photos of females, 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 raised to a level where the bias was greatly diminished.

However, this decision was reversed the next month after forces complained that the adjusted system was producing fewer “investigative leads”. NPCC documents show the stricter setting reduced the proportion of queries that yielded possible identifications from over half to a mere under 15%.

Severe Disparities

Although the Home Office and NPCC declined to specify what setting is currently used, the latest independent review found the system could produce false positives for Black women almost 100 times more frequently than for white women at specific configurations.

The Home Office commented on these findings: “The testing found that in a specific scenarios the software is has a greater tendency to wrongly flag some population segments in its match reports.”

Balancing Utility and Fairness

Describing the impact of the temporary raise to the system's accuracy setting, the NPCC documents state: “This adjustment significantly reduces the impact of discrimination across protected characteristics of race, generation and sex but had a significant negative impact on police efficiency”. The documents further note that forces argued that “a once effective tactic now delivered outcomes of limited benefit”.

Wider Implementation Proposals

Meanwhile, the government has launched a two-and-a-half-month consultation on its proposals to expand the use of biometric scanning systems. Policing minister the relevant minister has labeled the tool as the “biggest breakthrough since genetic fingerprinting”.

Criticism from Advisors and Monitors

The chair of a police oversight board, chair of the advisory panel for the national policing equality strategy, said: “There was very little consideration through race action plan meetings of the technology deployment even with clear relevance with the strategy's goals.

“This disclosure demonstrate once again that the anti-racism commitments policing has made through the race action plan are not being translated into wider practice. Our reports have warned that new technologies are being rolled out in a landscape where racial disparities, inadequate oversight and poor data collection continue to exist.

“All deployment of facial recognition must meet rigorous official guidelines, be independently scrutinised, and demonstrate it reduces rather than exacerbates ethnic bias.”

Home Office Response

A Home Office spokesperson stated: “We takes the conclusions of the report with utmost gravity and we have already taken action. A new algorithm has been independently tested and acquired, which has demonstrated no measurable discrimination. It will be tested in the coming months and will be undergo evaluation.

“The foremost aim is ensuring public safety. This revolutionary tool will assist police to apprehend and prosecute offenders. There is human involvement in each stage of the process and no further action would be pursued without specialist personnel carefully reviewing the output.”