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Police forces across the UK effectively campaigned to deploy a face scanning system acknowledged as discriminatory against women, youths, and individuals from minority ethnic backgrounds, after complaining that a more accurate version produced a reduced number of investigative leads.

The Technology in Practice

British police utilize the police national database (PND) to conduct retrospective facial recognition searches. This process entails matching a reference photograph of a person of interest against a repository of more than 19 million mugshots to identify potential matches.

Admitted Bias

The Home Office conceded last week that the technology was biased. This admission followed a study by the government's National Physical Laboratory determined it incorrectly matched people of Black and Asian heritage and females at significantly higher rates than Caucasian males. The Home Office stated it “took steps on the findings”.

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

Known Issue

Official papers show that this bias has been known about for more than a year. Furthermore, police forces argued to overturn an earlier ruling that was designed to address the problem.

Senior officers were notified of the system's bias in September 2024. The Home Office-commissioned NPL review concluded the system was had a higher probability to produce false positives for images depicting women, individuals of Black ethnicity, and those aged 40 and under.

A Reversed Decision

In reaction, the National Police Chiefs’ Council (NPCC) ordered 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 after forces complained that the adjusted system was producing a lower number of “investigative leads”. Internal records indicate the higher threshold cut the proportion of queries that yielded potential matches from over half to a mere under 15%.

Profound Inequalities

Although the authorities declined to specify what setting is currently used, the latest NPL study discovered the system could produce incorrect matches for women of Black heritage nearly a hundred times more often than for white women at specific configurations.

The ministry commented on these findings: “The testing identified that in a limited set of circumstances the algorithm is more likely to wrongly flag some demographic groups in its search results.”

Balancing Utility and Fairness

Outlining the impact of the temporary raise to the system's confidence threshold, the police records state: “This adjustment significantly reduces the impact of discrimination across legally safeguarded attributes of ethnicity, generation and sex but had a significant negative impact on operational effectiveness”. The papers further note that police units complained that “a once effective tactic returned outcomes of questionable value”.

Wider Implementation Proposals

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

Criticism from Advisors and Monitors

Abimbola Johnson, chair of the independent scrutiny and oversight board for the police race action plan, said: “We observed very little consideration in race action plan meetings of the technology deployment even with obvious cross-over with the strategy's goals.

“This disclosure demonstrate yet again that the pledges to combat discrimination policing has made through the equality initiative are failing to be integrated into wider practice. Independent assessments have warned that innovative tools are being implemented in a context where ethnic inequalities, inadequate oversight and faulty information gathering already persist.

“Any use of facial recognition must meet rigorous official guidelines, be independently scrutinised, and demonstrate it diminishes rather than exacerbates racial disparity.”

Official Statement

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

“Our priority is ensuring public safety. This gamechanging technology will support officers to apprehend and prosecute offenders. There is human involvement in each stage of the procedure and no further action would be pursued without trained officers carefully reviewing the results.”