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Law enforcement agencies across the UK successfully lobbied to use a face scanning system known to be discriminatory against females, youths, and individuals from ethnic minority groups, after complaining that a more accurate version produced fewer potential suspects.

The Technology in Practice

British police use the national police database to carry out retrospective facial recognition searches. This process involves matching a reference photograph of a person of interest against a repository of more than 19 million mugshots to find potential matches.

Admitted Bias

The Home Office admitted last week that the technology was biased. This acknowledgment followed a study by the government's National Physical Laboratory determined it incorrectly matched people of Black and Asian heritage and females at much greater frequency than white men. The Home Office stated it “took steps on the findings”.

“It prompts the question of whether facial recognition only becomes effective if users tolerate discrimination in ethnicity and sex. Convenience is a weak argument for overriding fundamental rights.”

Long-Standing Problem

Internal documents show that this bias has been recognized for over twelve months. Furthermore, law enforcement argued to overturn an initial decision that was designed to mitigate the problem.

Senior officers were informed of the algorithmic discrimination in September 2024. The government-ordered laboratory study found the system was had a higher probability to suggest incorrect matches for images depicting females, individuals of Black ethnicity, and those under 40 years old.

A Reversed Decision

In response, the National Police Chiefs’ Council (NPCC) mandated that the accuracy setting required for possible hits be increased to a level where the disparity was significantly reduced.

However, this directive was reversed the next month after forces complained that the modified technology was generating a lower number of “investigative leads”. NPCC documents indicate the higher threshold cut the number of searches that yielded potential matches from over half to a mere under 15%.

Profound Inequalities

Although the authorities refused to say what setting is currently used, the recent NPL study found the system could generate incorrect matches for women of Black heritage almost 100 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 demographic groups in its match reports.”

Operational Effectiveness vs. Bias

Describing the effect of the brief increase to the system's accuracy setting, the NPCC documents state: “The change greatly lessens the effect of bias across legally safeguarded attributes of ethnicity, age and gender but had a significant negative impact on police efficiency”. The papers add that forces complained that “a previously useful tool returned outcomes of questionable value”.

Wider Implementation Proposals

Meanwhile, the government has launched a two-and-a-half-month consultation on its proposals to expand the use of facial recognition technology. The minister for police Sarah Jones has described the technology as the “most significant advance since genetic fingerprinting”.

Expert and Oversight Concerns

The chair of a police oversight board, head of the independent scrutiny and oversight board for the police race action plan, said: “We observed very little consideration through equality strategy sessions of the facial recognition rollout despite obvious cross-over with the plan’s concerns.

“These revelations demonstrate once again that the anti-racism commitments the police has undertaken via the equality initiative are failing to be integrated into broader operations. Independent assessments have cautioned that innovative tools are being implemented in a context where racial disparities, weak scrutiny and faulty information gathering continue to exist.

“Any use of this technology must adhere to rigorous official guidelines, be subject to external review, and demonstrate it diminishes rather than exacerbates ethnic bias.”

Official Statement

A government representative stated: “The Home Office takes the findings of the study seriously and we have implemented changes. A updated software has been externally evaluated and acquired, which has no statistically significant bias. It will be tested early next year and will be subject to further assessment.

“The foremost aim is protecting the public. This gamechanging technology will support officers to put criminals and rapists behind bars. There is human involvement in every step of the procedure and no further action would be pursued without specialist personnel carefully reviewing the results.”