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Police forces across the United Kingdom successfully lobbied to use a face scanning system acknowledged as biased against females, young people, and members of minority ethnic backgrounds, after complaining that a less biased version produced a reduced number of potential suspects.

The Technology in Practice

British police utilize the national police database to carry out retrospective facial recognition searches. This procedure involves comparing a reference photograph of a person of interest against a database of over 19 million mugshots to identify potential matches.

Acknowledged Discrimination

The Home Office conceded last week that the system was biased. This acknowledgment came after a review by the government's National Physical Laboratory found it misidentified Black and Asian people and women at much greater frequency than Caucasian males. The ministry stated it “had acted on the findings”.

“This raises the issue of whether facial recognition only becomes effective if users tolerate discrimination in ethnicity and sex. Convenience is a weak argument for disregarding fundamental rights.”

Known Issue

Internal documents show that this discriminatory flaw has been recognized for more than a year. Furthermore, police forces argued to overturn an earlier ruling that was intended to mitigate the problem.

Senior officers were informed of the system's bias in September 2024. The Home Office-commissioned NPL review concluded the system was more likely to suggest false positives for images depicting females, individuals of Black ethnicity, and those under 40 years old.

A Reversed Decision

In reaction, the national police leadership body mandated that the accuracy setting required for possible hits be increased to a level where the bias was significantly reduced.

However, this decision was reversed the next month following complaints from police that the modified technology was generating fewer “useful lines of inquiry”. Internal records indicate the higher threshold reduced the proportion of queries resulting in potential matches from 56% to a mere 14%.

Profound Inequalities

Although the Home Office and NPCC refused to say what setting is currently used, the recent NPL study found the system could produce incorrect matches for Black women nearly a hundred times more frequently than for Caucasian women at specific configurations.

The Home Office stated on these findings: “Our evaluation found that in a specific scenarios the algorithm is more likely to wrongly flag some population segments in its search results.”

Operational Effectiveness vs. Bias

Describing the impact of the temporary raise to the system's confidence threshold, the police records note: “The change greatly lessens the impact of bias across protected characteristics of race, generation and sex but had a significant negative impact on police efficiency”. The documents add that police units argued that “a once effective tactic now delivered outcomes of limited benefit”.

Wider Implementation Proposals

Meanwhile, the UK administration has launched a two-and-a-half-month consultation on its plans to widen the use of facial recognition technology. Policing minister the relevant minister has labeled the tool as the “most significant advance since genetic fingerprinting”.

Expert and Oversight Concerns

The chair of a police oversight board, head of the advisory panel for the national policing equality strategy, commented: “We observed scant consideration through equality strategy sessions of the technology deployment despite obvious cross-over with the plan’s concerns.

“This disclosure demonstrate yet again that the pledges to combat discrimination the police has made through the race action plan are failing to be integrated into broader operations. Our reports have warned that new technologies are being implemented in a context where racial disparities, inadequate oversight and poor data collection already persist.

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

Home Office Response

A Home Office spokesperson said: “The Home Office treat the findings of the report with utmost gravity and we have implemented changes. A updated software has been externally evaluated and acquired, which has no statistically significant bias. It will be trialled in the coming months and will be undergo evaluation.

“Our priority is protecting the public. This revolutionary tool will assist police to apprehend and prosecute offenders. There is officer review in every step of the procedure and no arrest or charge would be pursued without trained officers carefully reviewing the output.”