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Police forces across the United Kingdom successfully lobbied to use a face scanning system known to be biased against women, young people, and individuals from ethnic minority groups, after complaining that a less biased version produced fewer potential suspects.

The Technology in Practice

British police utilize the police national database (PND) to carry out retrospective facial recognition searches. This process involves comparing a “probe image” of a person of interest against a database of over 19 million custody photos to find possible hits.

Acknowledged Discrimination

The UK interior ministry conceded last week that the system was flawed. This admission came after a study by the National Physical Laboratory (NPL) determined it misidentified Black and Asian people and women at significantly higher rates than Caucasian males. The ministry said it “had acted on the findings”.

“It prompts the issue of whether this technology only becomes useful if users accept discrimination in ethnicity and sex. Convenience is a poor argument for overriding basic freedoms.”

Long-Standing Problem

Internal documents show that this discriminatory flaw has been known about for over twelve months. Furthermore, police forces argued to overturn an initial decision that was intended to mitigate the problem.

Senior officers were notified of the system's bias in September 2024. The government-ordered laboratory study found the system was had a higher probability to produce false positives for images depicting females, Black people, and those aged 40 and under.

A Policy U-Turn

In reaction, the National Police Chiefs’ Council (NPCC) mandated that the accuracy setting required for potential matches be raised to a level where the bias was greatly diminished.

However, this decision was reversed the following month after forces complained that the modified technology was producing a lower number of “investigative leads”. Internal records indicate the higher threshold cut the proportion of queries resulting in possible identifications from over half to a just under 15%.

Severe Disparities

Although the authorities declined to specify what threshold is currently used, the latest independent review discovered the system could produce incorrect matches for women of Black heritage nearly a hundred times more often than for white women at certain settings.

The ministry stated on these results: “Our evaluation found that in a specific scenarios the software is more likely to wrongly flag some population segments in its search results.”

Balancing Utility and Fairness

Describing the impact of the temporary raise to the system's accuracy setting, the NPCC documents note: “This adjustment significantly reduces the impact of bias across protected characteristics of ethnicity, age and sex but had a substantially detrimental effect on operational effectiveness”. The documents further note that police units complained that “a once effective tactic now delivered results of questionable value”.

Wider Implementation Proposals

Meanwhile, the UK administration has launched a ten-week consultation on its proposals to widen the use of biometric scanning systems. The minister for police the relevant minister has labeled the tool as the “most significant advance since genetic fingerprinting”.

Criticism from Advisors and Monitors

The chair of a police oversight board, chair of the advisory panel for the national policing equality strategy, said: “There was very little discussion through equality strategy sessions of the technology deployment even with obvious cross-over with the plan’s concerns.

“These revelations show yet again that the anti-racism commitments the police has undertaken via the race action plan are failing to be integrated into wider practice. Our reports have warned that innovative tools are being rolled out in a landscape where racial disparities, inadequate oversight and faulty information gathering continue to exist.

“Any use of this technology must meet rigorous official guidelines, be subject to external review, and prove it reduces rather than compounds ethnic bias.”

Home Office Response

A government representative stated: “The Home Office takes the findings of the report with utmost gravity and we have implemented changes. A updated software has been independently tested and procured, which has no statistically significant bias. It will be trialled early next year and will be subject to further assessment.

“The foremost aim is ensuring public safety. This revolutionary tool will support police to apprehend and prosecute offenders. There is human involvement in each stage of the procedure and no arrest or charge would be taken without specialist personnel meticulously examining the output.”