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Police forces across the UK effectively campaigned to deploy a face scanning system acknowledged as discriminatory against women, youths, and individuals from ethnic minority groups, following complaints that a more accurate version produced a reduced number of investigative leads.

The Technology in Practice

UK forces use the police national database (PND) to conduct retrospective facial recognition searches. This process entails matching a reference photograph of a suspect against a repository of more than 19 million mugshots to find potential matches.

Admitted Bias

The Home Office admitted last week that the technology was flawed. This admission came after a study by the National Physical Laboratory (NPL) found it incorrectly matched Black and Asian people and females at significantly higher rates than white men. The ministry said it “had acted on the findings”.

“It prompts the question of whether this technology only becomes useful if users tolerate discrimination in race and sex. Convenience is a weak argument for overriding basic freedoms.”

Known Issue

Internal documents reveal that this bias has been known about for more than a year. Furthermore, police forces lobbied to reverse an earlier ruling that was designed to address the problem.

Police bosses were informed of the system's bias in September 2024. The Home Office-commissioned laboratory study found the system was had a higher probability to produce false positives for images depicting women, Black people, and those aged 40 and under.

A Policy U-Turn

In reaction, the national police leadership body ordered that the confidence threshold required for possible hits be raised to a point where the disparity was greatly diminished.

However, this directive was overturned the next month after forces complained that the adjusted system was producing a lower number of “investigative leads”. NPCC documents show the stricter setting cut the proportion of queries that yielded potential matches from over half to a just under 15%.

Profound Inequalities

Although the authorities refused to say what setting is currently used, the recent NPL study found the system could generate false positives for women of Black heritage nearly a hundred times more often than for white women at certain settings.

The Home Office stated on these findings: “Our evaluation identified that in a limited set of circumstances the software is has a greater tendency to wrongly flag some population segments in its search results.”

Operational Effectiveness vs. Bias

Outlining the impact of the temporary raise to the system's accuracy setting, the NPCC documents note: “The change significantly reduces the effect of bias across protected characteristics of ethnicity, age and gender but had a substantially detrimental effect on police efficiency”. The documents add that police units complained that “a previously useful tool returned results of limited benefit”.

Wider Implementation Proposals

Meanwhile, the UK administration has launched a two-and-a-half-month consultation on its proposals to expand the use of facial recognition technology. Policing minister 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, commented: “There was very little discussion through race action plan meetings of the facial recognition rollout even with clear relevance with the plan’s concerns.

“This disclosure demonstrate yet again that the pledges to combat discrimination the police has made through the equality initiative are not being translated into broader operations. Our reports have cautioned that innovative tools are being rolled out in a landscape where racial disparities, weak scrutiny and poor data collection already persist.

“All deployment of facial recognition must meet rigorous official guidelines, be independently scrutinised, and demonstrate it diminishes rather than compounds ethnic bias.”

Home Office Response

A government representative stated: “We takes the conclusions of the study 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 every step of the process and no further action would be pursued without specialist personnel carefully reviewing the output.”