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Law enforcement agencies across the UK effectively campaigned to use a face scanning system known to be discriminatory against women, youths, and members of ethnic minority groups, after complaining that a less biased version generated fewer potential suspects.

How the System Works

UK forces use the national police database to carry out searches using historical face recognition. This process involves comparing a “probe image” of a person of interest against a database of more than 19 million mugshots to identify potential matches.

Acknowledged Discrimination

The UK interior ministry admitted last week that the technology was flawed. This acknowledgment came after a study by the government's National Physical Laboratory determined it incorrectly matched people of Black and Asian heritage and women at much greater frequency than Caucasian males. The Home Office stated it “had acted on the findings”.

“This raises the issue of whether facial recognition only becomes effective if users tolerate discrimination in race and gender. Convenience is a weak argument for overriding fundamental rights.”

Known Issue

Official papers reveal that this bias has been known about for over twelve months. Furthermore, law enforcement lobbied to reverse an initial decision that was designed to mitigate the problem.

Police bosses were informed of the system's bias in September 2024. The government-ordered laboratory study found the system was more likely to produce incorrect matches for photos of women, Black people, and those aged 40 and under.

A Policy U-Turn

In reaction, the National Police Chiefs’ Council (NPCC) mandated that the confidence threshold required for potential matches be raised to a point where the bias was significantly reduced.

However, this directive was overturned the next month after forces complained that the adjusted system was generating a lower number of “useful lines of inquiry”. NPCC documents indicate the higher threshold cut the number of searches that yielded potential matches from 56% to a mere under 15%.

Severe Disparities

Although the Home Office and NPCC refused to say what setting is now in operation, the recent NPL study found the system could produce incorrect matches for women of Black heritage almost 100 times more often than for Caucasian women at specific configurations.

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

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 discrimination across protected characteristics of ethnicity, age and sex but had a substantially detrimental effect on operational effectiveness”. The documents add that forces complained that “a once effective tactic now delivered outcomes of questionable value”.

Broader Rollout Plans

Meanwhile, the UK administration has launched a ten-week consultation on its proposals to expand the use of biometric scanning systems. The minister for police Sarah Jones has labeled the tool as the “biggest breakthrough since DNA matching”.

Criticism from Advisors and Monitors

The chair of a police oversight board, head of the advisory panel for the national policing equality strategy, commented: “There was scant discussion through race action plan meetings of the facial recognition rollout despite clear relevance with the plan’s concerns.

“These revelations demonstrate yet again that the anti-racism commitments the police has undertaken via the race action plan are not being translated into wider practice. Our reports have warned that innovative tools are being implemented in a landscape where racial disparities, weak scrutiny and poor data collection already persist.

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

Home Office Response

A government representative stated: “The Home Office treat the conclusions of the study seriously and we have implemented changes. A updated software has been independently tested and acquired, which has demonstrated no measurable discrimination. It will be tested in the coming months and will be subject to evaluation.

“The foremost aim is protecting the public. This gamechanging technology will support police to apprehend and prosecute offenders. There is officer review in every step of the process and no further action would be pursued without trained officers meticulously examining the results.”