Police forces across the UK successfully lobbied to deploy a facial recognition system acknowledged as biased against women, youths, and individuals from minority ethnic backgrounds, after complaining that a less biased version produced a reduced number of investigative leads.
UK forces use the national police database to conduct searches using historical face recognition. This procedure entails matching a reference photograph of a person of interest against a database of more than 19 million mugshots to identify potential matches.
The Home Office admitted last week that the technology was biased. This admission came after a review by the National Physical Laboratory (NPL) found it incorrectly matched people of Black and Asian heritage and females at much greater frequency than Caucasian males. The Home Office stated it “took steps on the findings”.
“This raises the question of whether facial recognition only becomes effective if users accept discrimination in ethnicity and sex. Convenience is a poor argument for disregarding basic freedoms.”
Internal documents show that this discriminatory flaw has been known about for over twelve months. Furthermore, law enforcement argued to overturn an earlier ruling that was designed to mitigate the problem.
Senior officers were notified of the algorithmic discrimination in September 2024. The government-ordered laboratory study concluded the system was more likely to produce incorrect matches for images depicting women, individuals of Black ethnicity, and those under 40 years old.
In response, the National Police Chiefs’ Council (NPCC) mandated that the confidence threshold required for possible hits be raised to a level where the bias was greatly diminished.
However, this decision was overturned the following month after forces complained that the modified technology was producing a lower number of “useful lines of inquiry”. NPCC documents show the higher threshold reduced the number of searches resulting in possible identifications from over half to a just under 15%.
Although the authorities refused to say what threshold is currently used, the latest independent review found the system could generate false positives for Black women nearly a hundred times more often than for Caucasian women at certain settings.
The Home Office commented on these results: “The testing identified that in a specific scenarios the algorithm is has a greater tendency to incorrectly include some population segments in its search results.”
Outlining the impact of the brief increase to the system's confidence threshold, the police records state: “The change greatly lessens the effect of discrimination across protected characteristics of race, generation and sex but had a substantially detrimental effect on operational effectiveness”. The papers further note that police units argued that “a once effective tactic returned results of questionable value”.
Meanwhile, the government has opened a ten-week consultation on its plans 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”.
The chair of a police oversight board, chair of the advisory panel for the national policing equality strategy, commented: “We observed scant discussion through equality strategy sessions of the technology deployment even with obvious cross-over with the strategy's goals.
“This disclosure demonstrate yet again that the anti-racism commitments policing has undertaken via the equality initiative are not being translated into broader operations. Independent assessments have cautioned that new technologies are being implemented in a context where racial disparities, weak scrutiny and poor data collection already persist.
“All deployment of facial recognition must meet strict national standards, be independently scrutinised, and demonstrate it diminishes rather than compounds racial disparity.”
A government representative stated: “The Home Office takes the findings of the report seriously and we have already taken action. A updated software has been externally evaluated and acquired, which has demonstrated no measurable discrimination. It will be tested early next year and will be subject to evaluation.
“The foremost aim is protecting the public. This revolutionary tool will assist officers to put criminals and rapists behind bars. There is human involvement in every step of the procedure and no further action would be taken without trained officers carefully reviewing the output.”
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