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Police forces across the United Kingdom successfully lobbied to use a facial recognition system known to be discriminatory against women, youths, and individuals from ethnic minority groups, after complaining that a less biased version produced fewer investigative leads.

The Technology in Practice

UK forces use the national police database to carry out retrospective facial recognition searches. This process involves matching a “probe image” of a person of interest against a repository of over 19 million custody photos to find possible hits.

Acknowledged Discrimination

The Home Office conceded last week that the technology was biased. This acknowledgment came after a study by the government's National Physical Laboratory determined 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”.

“It prompts the question of whether this technology only becomes useful if users tolerate biases in race and sex. Operational ease is a weak argument for overriding fundamental rights.”

Known Issue

Internal documents reveal that this discriminatory flaw has been recognized for more than a year. 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 concluded the system was had a higher probability to suggest incorrect matches for images depicting females, individuals of Black ethnicity, and those aged 40 and under.

A Policy U-Turn

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

However, this directive was overturned the next month following complaints from police that the modified technology was producing a lower number of “useful lines of inquiry”. NPCC documents show the higher threshold reduced the proportion of queries resulting in potential matches from over half to a just 14%.

Profound Inequalities

Although the authorities declined to specify what setting is now in operation, the recent NPL study found 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 commented on these findings: “The testing identified that in a specific scenarios the algorithm is more likely to wrongly flag some demographic groups in its match reports.”

Balancing Utility and Fairness

Outlining the impact of the brief increase to the system's accuracy setting, the NPCC documents state: “The change significantly reduces the impact of discrimination across legally safeguarded attributes of ethnicity, age and gender but had a significant negative impact on police efficiency”. The documents further note that police units complained that “a previously useful tool returned outcomes of questionable value”.

Wider Implementation Proposals

Meanwhile, the government has launched a ten-week consultation on its proposals to widen the use of facial recognition technology. The minister for police the relevant minister has described the technology as the “biggest breakthrough since genetic fingerprinting”.

Criticism from Advisors and Monitors

The chair of a police oversight board, chair of the independent scrutiny and oversight board for the national policing equality strategy, said: “We observed very little discussion in race action plan meetings 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 made via the race action plan are not being translated into wider practice. Independent assessments have warned that innovative tools are being implemented in a context where ethnic inequalities, weak scrutiny and faulty information gathering already persist.

“Any use of this technology must meet rigorous official guidelines, be independently scrutinised, and prove it diminishes rather than exacerbates racial disparity.”

Home Office Response

A Home Office spokesperson said: “We treat the findings of the report seriously and we have already taken action. A updated software has been independently tested and procured, which has no statistically significant bias. It will be tested in the coming months and will be subject to further assessment.

“Our priority is protecting the public. 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.”