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Law enforcement agencies across the United Kingdom successfully lobbied to use a face scanning system acknowledged as discriminatory against women, youths, and members of minority ethnic backgrounds, following complaints that a less biased version generated fewer investigative leads.

How the System Works

British police utilize the national police database to conduct retrospective facial recognition searches. This procedure entails comparing a “probe image” of a suspect against a repository of more than 19 million custody photos to find possible hits.

Admitted Bias

The Home Office conceded last week that the system was biased. This admission came after a study by the National Physical Laboratory (NPL) determined it misidentified Black and Asian people and females at much greater frequency than Caucasian males. The Home Office said it “took steps on the findings”.

“It prompts the issue of whether this technology only becomes useful if users tolerate biases in ethnicity and gender. Convenience is a poor argument for overriding fundamental rights.”

Known Issue

Internal documents reveal that this discriminatory flaw has been known about for over twelve months. Furthermore, police forces lobbied to reverse an initial decision that was designed to mitigate the problem.

Senior officers were informed of the system's bias in September 2024. The government-ordered laboratory study concluded the system was more likely to suggest incorrect matches for photos of women, Black people, and those under 40 years old.

A Reversed Decision

In response, the National Police Chiefs’ Council (NPCC) mandated that the confidence threshold required for possible hits be increased to a point where the bias was greatly diminished.

However, this decision was reversed the following month following complaints from police that the adjusted system was producing fewer “useful lines of inquiry”. NPCC documents indicate the higher threshold reduced the number of queries resulting in possible identifications from over half to a mere under 15%.

Severe Disparities

Although the authorities refused to say what threshold is now in operation, the latest NPL study discovered the system could produce false positives for women of Black heritage almost 100 times more frequently than for Caucasian women at certain settings.

The ministry commented on these findings: “The testing found that in a limited set of circumstances the software is has a greater tendency to wrongly flag some population segments in its match reports.”

Balancing Utility and Fairness

Outlining the impact of the temporary raise to the system's confidence threshold, the police records note: “The change significantly reduces the effect of discrimination across protected characteristics of race, generation and gender but had a significant negative impact on police efficiency”. The papers further note that police units complained that “a once effective tactic now delivered results of limited benefit”.

Wider Implementation Proposals

Meanwhile, the UK administration has launched a two-and-a-half-month public review on its plans to expand the use of biometric scanning systems. The minister for police the relevant minister has labeled the technology as the “most significant advance 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, said: “There was very little discussion through race action plan meetings of the facial recognition rollout even with obvious cross-over with the strategy's goals.

“This disclosure show once again that the pledges to combat discrimination the police has made via the race action plan are not being translated into wider practice. Our reports have warned that innovative tools are being rolled out in a landscape where racial disparities, weak scrutiny and faulty information gathering already persist.

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

Official Statement

A government representative said: “We takes the findings of the report 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 evaluation.

“The foremost aim is ensuring public safety. This revolutionary tool will support officers to apprehend and prosecute offenders. There is officer review in every step of the procedure and no arrest or charge would be taken without trained officers meticulously examining the output.”