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Police forces across the UK effectively campaigned to use a face scanning system known to be biased against females, youths, and members of ethnic minority groups, following complaints that a less biased 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 entails comparing a “probe image” of a suspect against a database of over 19 million custody photos to identify possible hits.

Acknowledged Discrimination

The Home Office admitted last week that the system was biased. This admission came after a review by the National Physical Laboratory (NPL) determined it misidentified people of Black and Asian heritage and females at significantly higher rates than white men. The Home Office stated it “took steps on the findings”.

“This raises the issue of whether facial recognition only becomes useful if users tolerate discrimination in race and gender. Convenience is a weak argument for overriding fundamental rights.”

Long-Standing Problem

Official papers show that this discriminatory flaw has been known about for more than a year. Furthermore, law enforcement lobbied to reverse an initial decision that was intended to address the problem.

Police bosses were notified of the algorithmic discrimination in late 2024. The Home Office-commissioned laboratory study concluded the system was more likely to produce false positives for images depicting women, Black people, and those under 40 years old.

A Reversed Decision

In response, the national police leadership body ordered that the accuracy setting required for possible hits be increased to a point where the bias was greatly diminished.

However, this directive was overturned the following month following complaints from police that the modified technology was generating fewer “investigative leads”. NPCC documents show the higher threshold cut the proportion of queries that yielded possible identifications from over half to a mere 14%.

Profound Inequalities

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

The ministry commented on these results: “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.”

Balancing Utility and Fairness

Describing the impact of the brief increase to the system's accuracy setting, the police records state: “The change significantly reduces the effect of discrimination across legally safeguarded attributes of race, generation and gender but had a significant negative impact on operational effectiveness”. The papers further note that forces argued that “a previously useful tool returned results of questionable value”.

Broader Rollout Plans

Meanwhile, the government has launched a two-and-a-half-month consultation on its proposals to widen the use of biometric scanning systems. The minister for police the relevant minister has described the technology as the “biggest breakthrough since genetic fingerprinting”.

Criticism from Advisors and Monitors

Abimbola Johnson, head of the independent scrutiny and oversight board for the national policing equality strategy, commented: “There was very little consideration through equality strategy sessions of the technology deployment even with clear relevance with the strategy's goals.

“This disclosure demonstrate once again that the pledges to combat discrimination the police has undertaken via the equality initiative are not being translated into broader operations. Independent assessments have cautioned that innovative tools are being rolled out in a landscape where racial disparities, weak scrutiny and faulty information gathering already persist.

“Any use of this technology must meet strict national standards, be subject to external review, and demonstrate it reduces rather than exacerbates ethnic bias.”

Official Statement

A government representative stated: “We takes the findings of the study seriously and we have already taken action. A new algorithm has been externally evaluated and procured, which has demonstrated no measurable discrimination. It will be trialled early next year and will be undergo further assessment.

“The foremost aim is ensuring public safety. This revolutionary tool will support officers to put criminals and rapists behind bars. There is officer review in every step of the process and no further action would be pursued without specialist personnel carefully reviewing the results.”