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Law enforcement agencies across the United Kingdom successfully lobbied to use a face scanning system known to be discriminatory against women, young people, and individuals from ethnic minority groups, after complaining that a less biased version produced fewer potential suspects.

How the System Works

UK forces use the police national database (PND) to conduct retrospective facial recognition searches. This procedure entails comparing a reference photograph of a person of interest against a repository of more than 19 million custody photos to identify potential matches.

Acknowledged Discrimination

The Home Office conceded last week that the system was flawed. This admission followed a review by the National Physical Laboratory (NPL) determined it incorrectly matched Black and Asian people and women at much greater frequency than Caucasian males. The Home Office said it “took steps on the findings”.

“This raises the issue of whether this technology only becomes useful if users accept biases in race and gender. Operational ease is a weak argument for overriding fundamental rights.”

Known Issue

Internal documents show that this discriminatory flaw has been recognized for more than a year. Furthermore, law enforcement argued to overturn an initial decision that was intended to address the problem.

Police bosses were informed of the system's bias in late 2024. The Home Office-commissioned NPL review concluded the system was more likely to produce incorrect matches for images depicting women, Black people, and those aged 40 and under.

A Policy U-Turn

In response, the national police leadership body mandated that the confidence threshold required for potential matches be increased to a point where the disparity was greatly diminished.

However, this decision was overturned the following month after forces complained that the modified technology was generating fewer “useful lines of inquiry”. Internal records show the higher threshold cut the number of queries resulting in possible identifications from 56% to a mere under 15%.

Profound Inequalities

Although the authorities refused to say what setting is currently used, the recent NPL study found the system could generate false positives for Black women almost 100 times more often than for white women at specific configurations.

The ministry stated on these findings: “The testing identified that in a specific scenarios the software is has a greater tendency to incorrectly include some population segments in its match reports.”

Balancing Utility and Fairness

Describing the effect of the brief increase to the system's confidence threshold, the NPCC documents state: “This adjustment greatly lessens the impact of discrimination across legally safeguarded attributes of race, age and sex but had a substantially detrimental effect on operational effectiveness”. The documents further note that forces argued that “a previously useful tool now delivered outcomes of limited benefit”.

Broader Rollout Plans

Meanwhile, the UK administration has launched a two-and-a-half-month consultation on its proposals to widen the use of biometric scanning systems. The minister for police the relevant minister has described the tool as the “biggest breakthrough since DNA matching”.

Criticism from Advisors and Monitors

The chair of a police oversight board, head of the advisory panel for the police race action plan, commented: “We observed very little discussion through race action plan meetings of the facial recognition rollout despite clear relevance with the plan’s concerns.

“This disclosure demonstrate yet 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 cautioned that new technologies are being rolled out in a context where racial disparities, weak scrutiny and faulty information gathering already persist.

“Any use of this technology must adhere to strict national standards, be independently scrutinised, and prove it diminishes rather than compounds racial disparity.”

Official Statement

A government representative stated: “The Home Office takes the conclusions of the report with utmost gravity and we have already taken action. A new algorithm has been externally evaluated and acquired, which has demonstrated no measurable discrimination. It will be tested early next year and will be undergo further assessment.

“Our priority is protecting the public. This revolutionary tool will assist police to apprehend and prosecute offenders. There is officer review in each stage of the process and no arrest or charge would be taken without specialist personnel meticulously examining the results.”