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Law enforcement agencies across the UK successfully lobbied to use a face scanning system acknowledged as discriminatory against women, young people, and members of ethnic minority groups, after complaining that a less biased version produced a reduced number of potential suspects.

How the System Works

British police utilize the national police database to conduct searches using historical face recognition. This procedure entails matching a “probe image” of a person of interest against a database of over 19 million custody photos to find potential matches.

Admitted Bias

The UK interior ministry conceded last week that the system was flawed. This admission followed a review by the National Physical Laboratory (NPL) found it incorrectly matched Black and Asian people and females at much greater frequency than Caucasian males. The ministry stated it “had acted on the findings”.

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

Long-Standing Problem

Internal documents show that this bias has been recognized for more than a year. Furthermore, law enforcement argued to overturn an earlier ruling that was designed to mitigate the problem.

Senior officers were notified of the system's bias in late 2024. The government-ordered laboratory study concluded the system was had a higher probability to produce incorrect matches for images depicting females, Black people, and those aged 40 and under.

A Policy U-Turn

In reaction, the National Police Chiefs’ Council (NPCC) mandated that the accuracy setting required for potential matches be increased to a point where the bias was significantly reduced.

However, this directive was reversed the next month following complaints from police that the adjusted system was generating fewer “useful lines of inquiry”. Internal records show the stricter setting cut the proportion of queries resulting in possible identifications from over half to a just 14%.

Profound Inequalities

Although the Home Office and NPCC refused to say what threshold is currently used, the latest NPL study discovered the system could produce incorrect matches for Black women almost 100 times more often than for white women at specific configurations.

The Home Office stated on these findings: “The testing found that in a specific scenarios the algorithm is more likely to incorrectly include some demographic groups in its match reports.”

Balancing Utility and Fairness

Describing the impact of the temporary raise to the system's accuracy setting, the police records note: “This adjustment greatly lessens the impact of bias across protected characteristics of race, age and gender but had a significant negative impact on police efficiency”. The documents add that forces argued that “a once effective tactic now delivered results of questionable value”.

Wider Implementation Proposals

Meanwhile, the UK administration has launched a two-and-a-half-month public review on its proposals to widen the use of facial recognition technology. Policing minister the relevant minister has described the technology as the “biggest breakthrough since DNA matching”.

Criticism from Advisors and Monitors

Abimbola Johnson, head of the independent scrutiny and oversight board for the national policing equality strategy, commented: “There was very little consideration through equality strategy sessions of the technology deployment despite obvious cross-over with the strategy's goals.

“These revelations demonstrate once again that the anti-racism commitments the police has made through the equality initiative are failing to be integrated into wider practice. Independent assessments have warned that innovative tools are being implemented in a context where racial disparities, weak scrutiny and poor data collection already persist.

“All deployment of this technology must adhere to strict national standards, be independently scrutinised, and prove it reduces rather than compounds ethnic bias.”

Home Office Response

A government representative stated: “The Home Office treat the findings of the study seriously and we have implemented changes. A new algorithm has been externally evaluated and acquired, which has demonstrated no measurable discrimination. It will be trialled early next year and will be subject to further assessment.

“The foremost aim is ensuring public safety. This revolutionary tool will assist officers to put criminals and rapists behind bars. There is human involvement in each stage of the process and no further action would be taken without specialist personnel meticulously examining the output.”