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Police forces across the United Kingdom effectively campaigned to deploy a face scanning system known to be biased against females, young people, and members of ethnic minority groups, following complaints that a more accurate version generated a reduced number of investigative leads.

The Technology in Practice

UK forces use the national police database to conduct retrospective facial recognition searches. This process entails comparing a reference photograph of a person of interest against a database of over 19 million custody photos to find possible hits.

Admitted Bias

The UK interior ministry admitted last week that the technology was biased. This admission followed a study by the National Physical Laboratory (NPL) found it incorrectly matched Black and Asian people and females at much greater frequency than Caucasian males. The Home Office stated it “had acted on the findings”.

“This raises the question of whether this technology only becomes effective if users tolerate biases in ethnicity and gender. Convenience is a weak argument for disregarding basic freedoms.”

Known Issue

Official papers reveal that this bias 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 informed of the algorithmic discrimination in September 2024. The Home Office-commissioned NPL review found the system was more likely to produce false positives for photos of women, Black people, and those aged 40 and under.

A Reversed Decision

In response, the national police leadership body mandated that the accuracy setting required for potential matches be increased 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 fewer “useful lines of inquiry”. Internal records indicate the stricter setting reduced the proportion of searches that yielded possible identifications from 56% to a mere 14%.

Profound Inequalities

Although the authorities declined to specify what setting is now in operation, the recent independent review found the system could generate incorrect matches for women of Black heritage almost 100 times more frequently than for Caucasian women at certain settings.

The Home Office commented on these results: “The testing identified that in a specific scenarios the algorithm is more likely to incorrectly include some demographic groups in its match reports.”

Operational Effectiveness vs. Bias

Outlining the impact of the brief increase to the system's confidence threshold, the NPCC documents note: “The change significantly reduces the effect of bias across legally safeguarded attributes of ethnicity, age and sex but had a substantially detrimental effect on operational effectiveness”. The papers add that police units complained that “a once effective tactic now delivered outcomes of limited benefit”.

Broader Rollout Plans

Meanwhile, the UK administration has launched a ten-week consultation on its proposals to widen the use of biometric scanning systems. Policing minister the relevant minister has described the technology as the “most significant advance since DNA matching”.

Criticism from Advisors and Monitors

The chair of a police oversight board, head of the advisory panel for the national policing equality strategy, commented: “There was very little discussion in race action plan meetings of the facial recognition rollout even with clear relevance with the plan’s concerns.

“This disclosure show once again that the anti-racism commitments policing has undertaken through the equality initiative are not being translated into broader operations. Our reports have cautioned that new technologies are being rolled out in a context where ethnic inequalities, inadequate oversight and faulty information gathering continue to exist.

“Any use of facial recognition must meet strict national standards, be independently scrutinised, and demonstrate it diminishes rather than compounds ethnic bias.”

Official Statement

A government representative stated: “We treat the conclusions of the study seriously and we have implemented changes. 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 further assessment.

“Our priority is protecting the public. This gamechanging technology will assist police to apprehend and prosecute offenders. There is human involvement in every step of the procedure and no further action would be taken without specialist personnel carefully reviewing the output.”