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Law enforcement agencies across the UK effectively campaigned to use a facial recognition system known to be biased against women, youths, and members of minority ethnic backgrounds, after complaining that a less biased version produced a reduced number of potential suspects.

The Technology in Practice

UK forces utilize the national police database to conduct searches using historical face recognition. This process entails matching a “probe image” of a person of interest against a repository of over 19 million mugshots to identify possible hits.

Acknowledged Discrimination

The Home Office conceded last week that the technology was flawed. This admission came after a study by the government's National Physical Laboratory determined it misidentified Black and Asian people and women at much greater frequency than white men. The Home Office stated it “took steps on the findings”.

“This raises the question of whether this technology only becomes effective if users tolerate biases in race and gender. Operational ease is a poor argument for overriding fundamental rights.”

Known Issue

Internal documents reveal that this bias has been recognized for over twelve months. Furthermore, police forces argued to overturn an initial decision that was designed to mitigate the problem.

Senior officers were informed of the system's bias in September 2024. The Home Office-commissioned laboratory study concluded the system was more likely to suggest incorrect matches for photos of women, individuals of Black ethnicity, and those under 40 years old.

A Reversed Decision

In reaction, the National Police Chiefs’ Council (NPCC) mandated 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 modified technology was generating a lower number of “useful lines of inquiry”. Internal records indicate the higher threshold cut the proportion of queries resulting in possible identifications from 56% to a just 14%.

Profound Inequalities

Although the authorities declined to specify what threshold is now in operation, the recent NPL study found the system could produce false positives for Black women nearly a hundred times more frequently than for Caucasian women at certain settings.

The ministry commented on these results: “Our evaluation identified that in a specific scenarios the software is more likely to wrongly flag some demographic groups in its search results.”

Operational Effectiveness vs. Bias

Describing the impact of the brief increase 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 gender but had a significant negative impact on operational effectiveness”. The documents further note that forces argued that “a once effective tactic now delivered outcomes of questionable value”.

Broader Rollout Plans

Meanwhile, the UK administration has opened a ten-week public review on its proposals to widen the use of facial recognition technology. Policing minister Sarah Jones has described the tool as the “biggest breakthrough since genetic fingerprinting”.

Criticism from Advisors and Monitors

Abimbola Johnson, chair of the advisory panel for the national policing equality strategy, commented: “There was very little consideration in equality strategy sessions of the facial recognition rollout despite clear relevance with the plan’s concerns.

“These revelations demonstrate yet again that the pledges to combat discrimination the police has undertaken through the race action plan are failing to be integrated into wider practice. Our reports have warned that new technologies are being rolled out in a landscape where racial disparities, weak scrutiny and faulty information gathering continue to exist.

“All deployment of this technology must meet rigorous official guidelines, be independently scrutinised, and demonstrate it reduces rather than exacerbates ethnic bias.”

Home Office Response

A government representative stated: “We treat the conclusions of the study seriously and we have already taken action. A new algorithm has been independently tested and procured, which has no statistically significant bias. It will be trialled in the coming months and will be undergo further assessment.

“Our priority is ensuring public safety. This gamechanging technology will assist police to apprehend and prosecute offenders. There is officer review in every step of the process and no arrest or charge would be pursued without trained officers carefully reviewing the results.”