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Law enforcement agencies across the United Kingdom effectively campaigned to use a face scanning system known to be discriminatory against women, young people, and members of ethnic minority groups, after complaining that a more accurate version produced fewer investigative leads.

The Technology in Practice

UK forces use the national police database to carry out searches using historical face recognition. This procedure involves matching a reference photograph of a suspect against a repository of more than 19 million mugshots to find possible hits.

Acknowledged Discrimination

The UK interior ministry conceded last week that the system was biased. This acknowledgment came after a study by the National Physical Laboratory (NPL) found it incorrectly matched people of Black and Asian heritage and women at significantly higher rates than white men. The ministry stated it “took steps on the findings”.

“It prompts the question of whether this technology only becomes useful if users accept biases in ethnicity 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 over twelve months. Furthermore, law enforcement argued to overturn an earlier ruling that was intended to address the problem.

Police bosses were informed of the system's bias in September 2024. The government-ordered laboratory study found the system was had a higher probability to produce incorrect matches for photos of females, Black people, and those under 40 years old.

A Reversed Decision

In response, the national police leadership body ordered that the confidence threshold required for possible hits be raised to a level where the bias was significantly reduced.

However, this decision was reversed the following month after forces complained that the modified technology was producing fewer “useful lines of inquiry”. Internal records show the higher threshold reduced the proportion of searches resulting in possible identifications from 56% to a mere under 15%.

Profound Inequalities

Although the authorities declined to specify what threshold is now in operation, the recent independent review discovered the system could generate incorrect matches for Black women almost 100 times more often than for Caucasian women at specific configurations.

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

Balancing Utility and Fairness

Outlining the impact of the brief increase to the system's accuracy setting, the NPCC documents state: “This adjustment greatly lessens the effect of discrimination across protected characteristics of race, generation and gender but had a significant negative impact on operational effectiveness”. The papers add that forces argued that “a once effective tactic now delivered results of questionable value”.

Broader Rollout Plans

Meanwhile, the government has launched a two-and-a-half-month consultation on its plans to expand the use of facial recognition technology. The minister for police the relevant minister has labeled the tool as the “most significant advance since DNA matching”.

Criticism from Advisors and Monitors

Abimbola Johnson, head of the independent scrutiny and oversight board for the national policing equality strategy, said: “There was scant consideration through equality strategy sessions of the facial recognition rollout even with obvious cross-over with the plan’s concerns.

“This disclosure demonstrate once again that the anti-racism commitments the police has undertaken via the race action plan are failing to be integrated into wider practice. Our reports have warned that innovative tools are being implemented in a landscape where racial disparities, weak scrutiny and poor data collection continue to exist.

“All deployment of this technology must meet rigorous official guidelines, be subject to external review, and demonstrate it reduces rather than exacerbates ethnic bias.”

Home Office Response

A Home Office spokesperson stated: “The Home Office takes the findings of the study with utmost gravity and we have already taken action. A new algorithm has been externally evaluated and acquired, which has no statistically significant bias. It will be trialled in the coming months and will be subject to evaluation.

“The foremost aim is protecting the public. This revolutionary tool will assist police to apprehend and prosecute offenders. There is human involvement in each stage of the procedure and no further action would be pursued without specialist personnel meticulously examining the output.”