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Police forces across the UK successfully lobbied to use a face scanning system acknowledged as biased against women, young people, and individuals from ethnic minority groups, after complaining that a less biased version produced fewer investigative leads.

How the System Works

UK forces utilize the national police database to carry out searches using historical face recognition. This procedure entails matching a reference photograph of a suspect against a database of over 19 million custody photos to find potential matches.

Admitted Bias

The Home Office admitted last week that the technology was flawed. This acknowledgment followed 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 ministry said it “had acted on the findings”.

“This raises the question of whether this technology only becomes effective if users tolerate discrimination in race and sex. Convenience is a weak argument for disregarding fundamental rights.”

Known Issue

Official papers show that this bias has been recognized for more than a year. Furthermore, police forces argued to overturn an earlier ruling that was intended to mitigate the problem.

Senior officers were informed 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 females, individuals of Black ethnicity, and those under 40 years old.

A Reversed Decision

In reaction, the national police leadership body ordered that the accuracy setting required for potential matches be increased to a point where the disparity was greatly diminished.

However, this directive was overturned the following month following complaints from police that the modified technology was generating a lower number of “investigative leads”. NPCC documents show the higher threshold cut the number of queries that yielded potential matches from over half to a mere 14%.

Severe Disparities

Although the Home Office and NPCC declined to specify what setting is currently used, the recent independent review found the system could produce false positives for Black women nearly a hundred times more frequently than for Caucasian women at certain settings.

The Home Office stated on these findings: “Our evaluation found that in a specific scenarios the software is has a greater tendency to incorrectly include some demographic groups in its search results.”

Balancing Utility and Fairness

Describing the impact of the brief increase to the system's accuracy setting, the NPCC documents state: “This adjustment significantly reduces the impact of discrimination across protected characteristics of race, generation and gender but had a substantially detrimental effect on police efficiency”. The papers add that police units argued that “a once effective tactic returned results of limited benefit”.

Wider Implementation Proposals

Meanwhile, the UK administration has opened a ten-week public review on its proposals to expand the use of biometric scanning systems. The minister for police the relevant minister has labeled the technology as the “biggest breakthrough since genetic fingerprinting”.

Expert and Oversight Concerns

The chair of a police oversight board, chair of the advisory panel for the national policing equality strategy, said: “There was scant discussion through equality strategy sessions of the technology deployment even with obvious cross-over with the strategy's goals.

“These revelations show once again that the anti-racism commitments the police has made through the race action plan are failing to be integrated into wider practice. Our reports have cautioned that innovative tools are being rolled out in a context where racial disparities, inadequate oversight and poor data collection continue to exist.

“Any use of facial recognition must adhere to rigorous official guidelines, be subject to external review, and demonstrate it reduces rather than exacerbates ethnic bias.”

Home Office Response

A Home Office spokesperson stated: “We treat the conclusions of the study seriously and we have already taken action. A updated software has been independently tested and acquired, which has demonstrated no measurable discrimination. It will be tested early next year and will be undergo further assessment.

“Our priority is ensuring public safety. This gamechanging technology will assist officers to put criminals and rapists behind bars. There is human involvement in each stage of the process and no arrest or charge would be taken without specialist personnel meticulously examining the output.”