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Law enforcement agencies across the UK successfully lobbied to use a face scanning system acknowledged as discriminatory against women, youths, and members of minority ethnic backgrounds, after complaining that a more accurate version generated fewer investigative leads.

How the System Works

UK forces use the national police database to conduct retrospective facial recognition searches. This procedure entails comparing a reference photograph of a suspect against a database of more than 19 million mugshots to identify potential matches.

Acknowledged Discrimination

The UK interior ministry admitted last week that the system was flawed. This acknowledgment came after a study by the National Physical Laboratory (NPL) determined it incorrectly matched Black and Asian people and women at much greater frequency than white men. The ministry stated it “took steps on the findings”.

“This raises the issue of whether facial recognition only becomes effective if users accept discrimination in ethnicity and sex. Operational ease is a poor argument for overriding fundamental rights.”

Long-Standing Problem

Internal documents show that this bias has been recognized for more than a year. Furthermore, law enforcement argued to overturn an earlier ruling that was designed to address the problem.

Police bosses were informed of the system's bias in September 2024. The Home Office-commissioned NPL review found the system was had a higher probability to produce incorrect matches for images depicting women, individuals of Black ethnicity, and those under 40 years old.

A Reversed Decision

In reaction, the National Police Chiefs’ Council (NPCC) mandated that the confidence threshold required for possible hits be raised to a point where the disparity was significantly reduced.

However, this directive was reversed the next month after forces complained that the modified technology was producing a lower number of “investigative leads”. Internal records indicate the stricter setting cut the number of queries resulting in potential matches from 56% to a just under 15%.

Severe Disparities

Although the Home Office and NPCC declined to specify what threshold is now in operation, the latest independent review found the system could produce false positives for women of Black heritage nearly a hundred times more frequently than for white women at specific configurations.

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

Operational Effectiveness vs. Bias

Describing the effect of the brief increase to the system's confidence threshold, the NPCC documents state: “This adjustment significantly reduces the effect of bias across protected characteristics of race, age and gender but had a significant negative impact on operational effectiveness”. The papers further note that police units argued that “a previously useful tool now delivered outcomes of limited benefit”.

Wider Implementation Proposals

Meanwhile, the government has launched a ten-week consultation on its plans to expand the use of facial recognition technology. Policing minister the relevant minister has described the tool as the “biggest breakthrough since genetic fingerprinting”.

Criticism from Advisors and Monitors

Abimbola Johnson, head of the advisory panel for the police race action plan, commented: “There was very little discussion through equality strategy sessions of the facial recognition rollout despite clear relevance with the plan’s concerns.

“This disclosure demonstrate yet again that the pledges to combat discrimination policing has undertaken via the equality initiative are failing to be integrated into broader operations. Our reports have warned that innovative tools are being implemented in a context where ethnic inequalities, weak scrutiny and poor data collection continue to exist.

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

Home Office Response

A government representative said: “We takes the findings of the report with utmost gravity and we have already taken action. A updated software has been externally evaluated and acquired, which has no statistically significant bias. It will be trialled early next year and will be subject to evaluation.

“The foremost aim is protecting the public. This gamechanging technology will assist police to apprehend and prosecute offenders. There is human involvement in every step of the process and no arrest or charge would be pursued without trained officers carefully reviewing the results.”