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Police forces across the UK successfully lobbied to deploy a facial recognition system acknowledged as biased against women, young people, and individuals from ethnic minority groups, after complaining that a less biased version generated a reduced number of potential suspects.

How the System Works

UK forces utilize the police national database (PND) to conduct retrospective facial recognition searches. This process entails matching a reference photograph of a person of interest against a repository of over 19 million custody photos to find possible hits.

Admitted Bias

The Home Office conceded last week that the technology was biased. This acknowledgment followed a study by the government's National Physical Laboratory found it incorrectly matched Black and Asian people and women at significantly higher rates than white men. The Home Office stated it “took steps on the findings”.

“It prompts the question of whether facial recognition only becomes useful if users accept biases in ethnicity and gender. Convenience is a poor argument for disregarding fundamental rights.”

Known Issue

Official papers reveal that this bias has been known about for more than a year. Furthermore, police forces lobbied to reverse an initial decision that was designed to mitigate the problem.

Police bosses were notified of the algorithmic discrimination in September 2024. The Home Office-commissioned NPL review concluded the system was had a higher probability to suggest false positives for photos of females, Black people, and those under 40 years old.

A Reversed Decision

In response, the national police leadership body ordered that the accuracy setting required for possible hits be raised to a point where the disparity was greatly diminished.

However, this decision was overturned the following month following complaints from police that the adjusted system was generating a lower number of “investigative leads”. Internal records indicate the stricter setting cut the number of searches resulting in potential matches from over half to a just under 15%.

Profound Inequalities

Although the Home Office and NPCC declined to specify what setting is now in operation, the latest independent review discovered the system could generate incorrect matches for women of Black heritage almost 100 times more frequently than for white women at specific configurations.

The ministry stated on these results: “The testing found that in a specific scenarios the algorithm is has a greater tendency to wrongly flag some demographic groups in its search results.”

Operational Effectiveness vs. Bias

Describing the effect of the brief increase to the system's confidence threshold, the NPCC documents note: “The change significantly reduces the effect of bias across protected characteristics of ethnicity, generation and sex but had a significant negative impact on operational effectiveness”. The papers add that forces argued that “a previously useful tool returned outcomes of limited benefit”.

Broader Rollout Plans

Meanwhile, the UK administration has opened a ten-week consultation on its proposals to widen the use of facial recognition technology. The minister for police the relevant minister has described the technology as the “most significant advance since genetic fingerprinting”.

Criticism from Advisors and Monitors

The chair of a police oversight board, chair of the independent scrutiny and oversight board for the national policing equality strategy, commented: “We observed very little discussion in race action plan meetings of the facial recognition rollout even with clear relevance with the plan’s concerns.

“This disclosure show once again that the pledges to combat discrimination the police has made through the equality initiative are not being translated into wider practice. Our reports have cautioned that innovative tools are being implemented in a landscape where racial disparities, weak scrutiny and poor data collection continue to exist.

“All deployment of this technology must meet strict national standards, be independently scrutinised, and demonstrate it diminishes rather than exacerbates racial disparity.”

Home Office Response

A Home Office spokesperson said: “We treat the findings of the report seriously and we have implemented changes. A new algorithm has been externally evaluated and procured, which has no statistically significant bias. It will be tested early next year and will be subject to further assessment.

“Our priority is ensuring public safety. This gamechanging technology will support 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 specialist personnel meticulously examining the output.”