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Police forces across the UK successfully lobbied to use a face scanning system known to be biased against females, young people, and individuals from minority ethnic backgrounds, after complaining that a more accurate version generated fewer potential suspects.

The Technology in Practice

UK forces use the police national database (PND) to carry out retrospective facial recognition searches. This process involves matching a reference photograph of a suspect against a repository of over 19 million custody photos to find possible hits.

Admitted Bias

The Home Office conceded last week that the technology was biased. This admission followed a study by the National Physical Laboratory (NPL) found it misidentified Black and Asian people and women at much greater frequency than Caucasian males. The ministry said it “took steps on the findings”.

“This raises the question of whether facial recognition only becomes useful if users tolerate discrimination in ethnicity and sex. Convenience is a poor argument for disregarding basic freedoms.”

Known Issue

Internal documents reveal that this discriminatory flaw has been recognized for more than a year. Furthermore, law enforcement argued to overturn an initial decision that was intended to mitigate the problem.

Senior officers were informed of the algorithmic discrimination in September 2024. The Home Office-commissioned laboratory study concluded the system was had a higher probability to suggest incorrect matches for images depicting females, individuals of Black ethnicity, and those aged 40 and under.

A Policy U-Turn

In response, the national police leadership body ordered that the confidence threshold required for potential matches be increased to a level where the bias was greatly diminished.

However, this directive was overturned the next month after forces complained that the adjusted system was producing a lower number of “useful lines of inquiry”. Internal records show the stricter setting reduced the proportion of queries that yielded potential matches from 56% to a mere 14%.

Profound Inequalities

Although the authorities declined to specify what threshold is currently used, the latest independent review discovered the system could generate false positives for women of Black heritage almost 100 times more frequently than for Caucasian women at certain settings.

The Home Office commented on these findings: “Our evaluation identified that in a specific scenarios the software is more likely to incorrectly include some population segments in its search results.”

Operational Effectiveness vs. Bias

Describing the effect of the brief increase to the system's accuracy setting, the NPCC documents note: “The change greatly lessens the impact of bias across protected characteristics of race, generation and sex but had a substantially detrimental effect on operational effectiveness”. The documents add that police units argued that “a once effective tactic returned results of questionable value”.

Broader Rollout Plans

Meanwhile, the government has launched a ten-week consultation on its plans to expand the use of facial recognition technology. Policing minister Sarah Jones has labeled the tool as the “most significant advance since genetic fingerprinting”.

Expert and Oversight Concerns

Abimbola Johnson, head of the advisory panel for the police race action plan, said: “There was very little discussion in race action plan meetings of the technology deployment even with clear relevance with the strategy's goals.

“This disclosure show once again that the pledges to combat discrimination policing has undertaken via the equality initiative are failing to be integrated into broader operations. Independent assessments have cautioned that innovative tools are being rolled out in a context where ethnic inequalities, weak scrutiny and poor data collection already persist.

“All deployment of this technology must meet strict national standards, be independently scrutinised, and prove it diminishes rather than exacerbates ethnic bias.”

Official Statement

A Home Office spokesperson stated: “We treat the conclusions of the report with utmost gravity and we have implemented changes. A updated software has been independently tested and acquired, which has no statistically significant bias. It will be trialled early next year and will be subject to further assessment.

“Our priority is protecting the public. This revolutionary tool will assist officers to apprehend and prosecute offenders. There is officer review in every step of the procedure and no further action would be pursued without trained officers carefully reviewing the results.”