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Police forces across the United Kingdom successfully lobbied to use a facial recognition system known to be biased against women, young people, and members of minority ethnic backgrounds, after complaining that a less biased version produced fewer potential suspects.

The Technology in Practice

UK forces use the police national database (PND) to carry out searches using historical face recognition. This process involves matching a reference photograph of a suspect against a repository of more than 19 million custody photos to find potential matches.

Acknowledged Discrimination

The UK interior ministry conceded last week that the technology was flawed. This acknowledgment came after a review by the government's National Physical Laboratory found it misidentified people of Black and Asian heritage and women 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 ethnicity and gender. Convenience is a poor argument for overriding basic freedoms.”

Known Issue

Internal documents show that this discriminatory flaw has been known about 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 Home Office-commissioned laboratory study concluded the system was had a higher probability 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 leadership body mandated that the confidence threshold required for potential matches be raised to a level where the disparity was greatly diminished.

However, this decision was overturned the following month following complaints from police that the adjusted system was producing a lower number of “investigative leads”. Internal records indicate the higher threshold reduced the proportion of searches that yielded potential matches from 56% to a just under 15%.

Severe Disparities

Although the authorities declined to specify what setting is now in operation, the recent independent review found the system could produce incorrect matches for Black women almost 100 times more often than for Caucasian women at specific configurations.

The ministry stated on these findings: “The testing identified that in a specific scenarios the software is has a greater tendency to incorrectly include some population segments in its search results.”

Balancing Utility and Fairness

Describing the impact of the brief increase to the system's confidence threshold, the police records state: “The change greatly lessens the impact of discrimination across protected characteristics of ethnicity, generation and gender but had a significant negative impact on operational effectiveness”. The papers add that forces argued that “a previously useful tool now delivered outcomes of limited benefit”.

Wider Implementation Proposals

Meanwhile, the government has opened a ten-week consultation on its proposals to widen the use of biometric scanning systems. Policing minister the relevant minister has labeled the technology as the “most significant advance since genetic fingerprinting”.

Expert and Oversight Concerns

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 consideration through race action plan meetings of the facial recognition rollout despite obvious cross-over with the strategy's goals.

“This disclosure demonstrate yet again that the anti-racism commitments the police has undertaken through the race action plan are not being translated into wider practice. Independent assessments have warned that new technologies are being implemented in a landscape where racial disparities, weak scrutiny and faulty information gathering already persist.

“All deployment of facial recognition must meet rigorous official guidelines, be independently scrutinised, and prove it reduces rather than compounds racial disparity.”

Home Office Response

A government representative said: “We takes the conclusions of the study seriously and we have already taken action. A updated software has been independently tested and procured, which has demonstrated no measurable discrimination. It will be trialled in the coming months and will be subject to further assessment.

“Our priority is ensuring public safety. This revolutionary tool will assist police to put criminals and rapists behind bars. There is human involvement in each stage of the process and no arrest or charge would be pursued without trained officers carefully reviewing the output.”