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Police forces across the UK successfully lobbied to deploy a face scanning system known to be discriminatory against females, youths, and individuals from minority ethnic backgrounds, following complaints that a more accurate version generated fewer potential suspects.

The Technology in Practice

British police utilize the police national database (PND) to carry out retrospective facial recognition searches. This process entails matching a “probe image” of a suspect against a repository of more than 19 million mugshots to find possible hits.

Admitted Bias

The Home Office admitted last week that the technology was biased. This acknowledgment followed a review by the National Physical Laboratory (NPL) determined it misidentified people of Black and Asian heritage and women at much greater frequency than white men. The ministry stated it “took steps on the findings”.

“This raises the question of whether this technology only becomes useful if users tolerate biases in ethnicity and gender. Operational ease is a poor argument for overriding basic freedoms.”

Long-Standing Problem

Internal documents show 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.

Police bosses were notified of the algorithmic discrimination in September 2024. The government-ordered laboratory study concluded the system was more likely to produce incorrect matches for photos of females, Black people, and those aged 40 and under.

A Reversed Decision

In response, the national police leadership body mandated that the accuracy setting required for potential matches be raised to a level where the bias was greatly diminished.

However, this directive was overturned the next month following complaints from police that the adjusted system was generating a lower number of “useful lines of inquiry”. Internal records indicate the higher threshold reduced the number of queries resulting in potential matches from over half to a just 14%.

Profound Inequalities

Although the authorities refused to say what setting is now in operation, the latest independent review found the system could generate false positives for women of Black heritage nearly a hundred times more frequently than for Caucasian women at certain settings.

The ministry commented on these results: “Our evaluation identified that in a specific scenarios the algorithm is more likely to wrongly flag some demographic groups in its search results.”

Balancing Utility and Fairness

Describing the effect of the temporary raise to the system's confidence threshold, the police records state: “This adjustment significantly reduces the impact of discrimination across protected characteristics of ethnicity, generation and sex but had a significant negative impact on police efficiency”. The papers add that forces complained that “a previously useful tool returned results of questionable value”.

Wider Implementation Proposals

Meanwhile, the UK administration has launched a two-and-a-half-month public review on its plans to widen the use of facial recognition technology. The minister for police Sarah Jones 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 national policing equality strategy, said: “We observed scant discussion through equality strategy sessions of the technology deployment despite clear relevance with the strategy's goals.

“These revelations show once again that the pledges to combat discrimination the police has made through the race action plan are not being translated into broader operations. Our reports have cautioned that innovative tools are being rolled out in a landscape where racial disparities, weak scrutiny and faulty information gathering already persist.

“All deployment of facial recognition must meet strict national standards, be subject to external review, and demonstrate it diminishes rather than exacerbates racial disparity.”

Home Office Response

A government representative said: “The Home Office takes the conclusions of the study seriously and we have already taken action. A updated software has been externally evaluated and acquired, which has demonstrated no measurable discrimination. It will be trialled in the coming months and will be undergo further assessment.

“Our priority is ensuring public safety. This revolutionary tool will support police to apprehend and prosecute offenders. There is officer review in every step of the process and no further action would be pursued without trained officers meticulously examining the output.”