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Police forces across the UK effectively campaigned to use a face scanning system known to be discriminatory against women, young people, and members of ethnic minority groups, following complaints that a less biased version produced fewer investigative leads.

The Technology in Practice

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

Acknowledged Discrimination

The Home Office conceded last week that the technology was biased. This admission followed a study by the government's National Physical Laboratory determined it incorrectly matched Black and Asian people and females at much greater frequency than white men. The ministry stated it “took steps on the findings”.

“This raises the question of whether this technology only becomes useful if users tolerate biases in race and gender. Convenience is a weak argument for overriding basic freedoms.”

Known Issue

Internal documents reveal that this bias has been recognized for more than a year. Furthermore, law enforcement lobbied to reverse an earlier ruling that was intended to mitigate the problem.

Police bosses were informed of the algorithmic discrimination in September 2024. The Home Office-commissioned laboratory study found the system was had a higher probability to suggest false positives for images depicting females, individuals of Black ethnicity, and those under 40 years old.

A Reversed Decision

In reaction, the National Police Chiefs’ Council (NPCC) ordered that the accuracy setting required for potential matches be raised to a level where the disparity was greatly diminished.

However, this directive was reversed the next month after forces complained that the modified technology was producing fewer “investigative leads”. Internal records indicate the higher threshold cut the number of queries resulting in potential matches from over half to a mere 14%.

Severe Disparities

Although the authorities refused to say what setting is currently used, the recent independent review found the system could produce false positives for women of Black heritage almost 100 times more frequently than for white women at certain settings.

The Home Office stated on these results: “Our evaluation found that in a specific scenarios the algorithm is has a greater tendency to incorrectly include some population segments in its match reports.”

Operational Effectiveness vs. Bias

Describing the impact of the brief increase to the system's accuracy setting, the NPCC documents state: “This adjustment greatly lessens the effect of discrimination across protected characteristics of race, age and gender but had a significant negative impact on police efficiency”. The papers add that police units complained that “a previously useful tool now delivered results of questionable value”.

Broader Rollout Plans

Meanwhile, the government has opened a ten-week public review on its proposals to expand the use of facial recognition technology. Policing minister the relevant minister has labeled the tool as the “biggest breakthrough since DNA matching”.

Expert and Oversight Concerns

The chair of a police oversight board, head of the independent scrutiny and oversight board for the police race action plan, said: “There was scant consideration in race action plan meetings of the technology deployment even with clear relevance with the strategy's goals.

“This disclosure show once again that the pledges to combat discrimination the police has made via the equality initiative are failing to be integrated into wider practice. Independent assessments have warned that innovative tools are being implemented in a landscape where racial disparities, inadequate oversight and poor data collection continue to exist.

“Any use of this technology must adhere to strict national standards, be subject to external review, and prove it reduces rather than compounds racial disparity.”

Home Office Response

A Home Office spokesperson stated: “The Home Office treat the conclusions of the study with utmost gravity and we have already taken action. A new algorithm has been independently tested and procured, which has demonstrated no measurable discrimination. It will be tested early next year and will be subject to further assessment.

“The foremost aim is ensuring public safety. This revolutionary tool will support officers to put criminals and rapists behind bars. There is officer review in each stage of the process and no arrest or charge would be pursued without trained officers meticulously examining the output.”