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Police forces across the United Kingdom successfully lobbied to deploy a face scanning system known to be biased against women, youths, and members of minority ethnic backgrounds, after complaining that a less biased version generated a reduced number of potential suspects.

The Technology in Practice

UK forces use the police national database (PND) to conduct searches using historical face recognition. This procedure involves comparing a “probe image” of a person of interest against a repository of more than 19 million mugshots to find possible hits.

Acknowledged Discrimination

The UK interior ministry conceded last week that the technology was biased. This acknowledgment came after a study by the government's National Physical Laboratory found it incorrectly matched Black and Asian people and women at much greater frequency than white men. The Home Office said it “had acted on the findings”.

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

Known Issue

Official papers show that this discriminatory flaw has been recognized for more than a year. Furthermore, law enforcement lobbied to reverse an earlier ruling that was designed to mitigate the problem.

Senior officers were notified of the algorithmic discrimination in late 2024. The government-ordered laboratory study found the system was more likely to suggest incorrect matches for photos of females, Black people, and those aged 40 and under.

A Policy U-Turn

In response, the national police leadership body ordered that the confidence threshold required for possible hits be raised to a level where the disparity was significantly reduced.

However, this directive was overturned the following month after forces complained that the adjusted system was producing fewer “investigative leads”. Internal records show the higher threshold cut the proportion of searches that yielded potential matches from over half to a just 14%.

Severe Disparities

Although the Home Office and NPCC refused to say what setting is currently used, the recent NPL study found the system could produce incorrect matches for Black women nearly a hundred times more often than for white women at specific configurations.

The ministry stated on these results: “Our evaluation identified that in a limited set of circumstances the algorithm is has a greater tendency to wrongly flag some demographic groups in its match reports.”

Balancing Utility and Fairness

Outlining the impact of the temporary raise to the system's accuracy setting, the police records state: “The change significantly reduces the impact of discrimination across protected characteristics of race, age and sex but had a substantially detrimental effect on police efficiency”. The documents further note that police units argued that “a previously useful tool returned results of limited benefit”.

Wider Implementation Proposals

Meanwhile, the UK administration has opened a ten-week public review on its plans to expand the use of facial recognition technology. Policing minister Sarah Jones has described the technology as the “biggest breakthrough since DNA matching”.

Expert and Oversight Concerns

The chair of a police oversight board, chair of the advisory panel for the police race action plan, commented: “There was scant discussion in equality strategy sessions of the technology deployment even with clear relevance with the plan’s concerns.

“These revelations show once again that the pledges to combat discrimination policing has undertaken via the equality initiative are failing to be integrated into wider practice. Independent assessments have warned that new technologies are being implemented in a context where ethnic inequalities, weak scrutiny and poor data collection already persist.

“All deployment of this technology must adhere to strict national standards, be independently scrutinised, and prove it diminishes rather than exacerbates racial disparity.”

Official Statement

A Home Office spokesperson said: “We takes the conclusions of the study seriously and we have already taken action. A new algorithm has been externally evaluated and acquired, which has no statistically significant bias. It will be trialled early next year and will be undergo evaluation.

“Our priority is ensuring public safety. This revolutionary tool will support police to apprehend and prosecute offenders. There is human involvement in every step of the procedure and no further action would be pursued without trained officers meticulously examining the results.”