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Law enforcement agencies across the UK successfully lobbied to deploy a face scanning system acknowledged as biased against females, young people, and individuals from minority ethnic backgrounds, after complaining that a less biased version produced fewer investigative leads.

How the System Works

British police utilize the national police database to conduct retrospective facial recognition searches. This process entails matching a “probe image” of a person of interest against a database of over 19 million mugshots to find potential matches.

Admitted Bias

The Home Office admitted last week that the system was biased. This acknowledgment came after a study by the National Physical Laboratory (NPL) determined it incorrectly matched people of Black and Asian heritage and women at significantly higher rates than white men. The ministry said it “took steps on the findings”.

“This raises the issue of whether this technology only becomes effective if users accept discrimination in race and gender. Convenience is a poor argument for disregarding basic freedoms.”

Known Issue

Official papers reveal that this discriminatory flaw has been known about for over twelve months. Furthermore, law enforcement lobbied to reverse an earlier ruling that was designed to address the problem.

Police bosses were notified of the algorithmic discrimination in late 2024. The Home Office-commissioned NPL review concluded the system was had a higher probability to produce incorrect matches for images depicting women, individuals of Black ethnicity, and those aged 40 and under.

A Policy U-Turn

In response, the National Police Chiefs’ Council (NPCC) mandated that the accuracy setting required for potential matches be increased to a point where the disparity was greatly diminished.

However, this directive was overturned the next month after forces complained that the modified technology was producing fewer “useful lines of inquiry”. NPCC documents indicate the higher threshold reduced the number of queries resulting in possible identifications from 56% to a mere 14%.

Severe Disparities

Although the authorities refused to say what setting is now in operation, the recent NPL study found the system could produce false positives for women of Black heritage almost 100 times more often than for Caucasian women at specific configurations.

The Home Office commented on these results: “The testing found that in a limited set of circumstances the software is more likely to incorrectly include some population segments in its search results.”

Operational Effectiveness vs. Bias

Describing the effect of the temporary raise to the system's confidence threshold, the NPCC documents note: “This adjustment significantly reduces the effect of bias across protected characteristics of race, generation and gender but had a significant negative impact on police efficiency”. The papers further note that forces argued that “a once effective tactic returned results of limited benefit”.

Wider Implementation Proposals

Meanwhile, the government has launched a two-and-a-half-month public review on its plans to expand the use of biometric scanning systems. The minister for police Sarah Jones has labeled the tool as the “most significant advance since DNA matching”.

Expert and Oversight Concerns

Abimbola Johnson, chair of the advisory panel for the police race action plan, said: “We observed scant consideration through equality strategy sessions of the technology deployment even with obvious cross-over with the strategy's goals.

“These revelations show yet again that the anti-racism commitments the police has undertaken through the equality initiative are not being translated into broader operations. Independent assessments have cautioned that new technologies are being rolled out in a context where racial disparities, inadequate oversight and faulty information gathering already persist.

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

Home Office Response

A Home Office spokesperson said: “We treat the findings 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 in the coming months 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 arrest or charge would be pursued without trained officers meticulously examining the results.”