Police forces across the UK successfully lobbied to use a facial recognition system acknowledged as biased against women, young people, and individuals from ethnic minority groups, after complaining that a more accurate version generated a reduced number of potential suspects.
UK forces use the police national database (PND) to conduct retrospective facial recognition searches. This procedure involves comparing a reference photograph of a suspect against a database of over 19 million custody photos to identify possible hits.
The Home Office conceded last week that the technology was flawed. This acknowledgment followed a review by the National Physical Laboratory (NPL) found it misidentified people of Black and Asian heritage and females at much greater frequency than Caucasian males. The ministry said it “had acted on the findings”.
“This raises the question of whether facial recognition only becomes useful if users accept discrimination in race and gender. Convenience is a weak argument for disregarding fundamental rights.”
Internal documents reveal that this discriminatory flaw 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.
Senior officers were notified of the algorithmic discrimination in September 2024. The government-ordered laboratory study concluded the system was had a higher probability to suggest false positives for images depicting women, individuals of Black ethnicity, and those under 40 years old.
In reaction, the National Police Chiefs’ Council (NPCC) mandated that the confidence threshold required for possible hits be increased to a point where the bias was greatly diminished.
However, this decision was overturned the following month after forces complained that the adjusted system was producing a lower number of “investigative leads”. NPCC documents indicate the higher threshold cut the number of queries that yielded potential matches from over half to a just 14%.
Although the authorities declined to specify what threshold is now in operation, the latest NPL study found the system could produce incorrect matches for Black women nearly a hundred times more frequently than for white women at certain settings.
The Home Office stated 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.”
Outlining the effect of the brief increase to the system's accuracy setting, the NPCC documents state: “The change greatly lessens the impact of discrimination across protected characteristics of race, generation and gender but had a significant negative impact on operational effectiveness”. The papers add that forces argued that “a previously useful tool returned results of limited benefit”.
Meanwhile, the government has opened a two-and-a-half-month consultation on its plans to widen the use of facial recognition technology. Policing minister Sarah Jones has labeled the technology as the “biggest breakthrough since genetic fingerprinting”.
The chair of a police oversight board, head of the advisory panel for the police race action plan, said: “We observed scant discussion in equality strategy sessions of the facial recognition rollout even with obvious cross-over with the strategy's goals.
“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 cautioned that new technologies are being rolled out in a context where ethnic inequalities, inadequate oversight and faulty information gathering already persist.
“All deployment of this technology must meet strict national standards, be subject to external review, and demonstrate it diminishes rather than compounds ethnic bias.”
A government representative said: “The Home Office treat the conclusions of the report seriously and we have already taken action. A new algorithm has been independently tested and procured, which has demonstrated no measurable discrimination. It will be trialled in the coming months and will be undergo further assessment.
“The foremost aim is protecting the public. This revolutionary tool will assist police to put criminals and rapists behind bars. There is officer review in every step of the procedure and no further action would be pursued without specialist personnel carefully reviewing the output.”
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