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Police forces across the UK effectively campaigned 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 generated fewer investigative leads.

The Technology in Practice

British police utilize the police national database (PND) to conduct searches using historical face recognition. This procedure entails matching a “probe image” of a suspect against a database of over 19 million mugshots to find potential matches.

Admitted Bias

The Home Office admitted last week that the technology was biased. 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 significantly higher rates than Caucasian males. The Home Office stated it “took steps on the findings”.

“This raises the question of whether facial recognition only becomes useful if users tolerate discrimination in race and sex. Operational ease is a poor argument for overriding basic freedoms.”

Long-Standing Problem

Official papers show that this discriminatory flaw has been recognized for over twelve months. Furthermore, police forces lobbied to reverse 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 found the system was more likely to suggest incorrect matches for images depicting women, individuals of Black ethnicity, and those under 40 years old.

A Reversed Decision

In response, the national police leadership body mandated that the confidence threshold required for possible hits be raised to a point where the bias was greatly diminished.

However, this directive was reversed the following month after forces complained that the modified technology was producing fewer “useful lines of inquiry”. Internal records indicate the stricter setting reduced the number of searches resulting in possible identifications from 56% to a just 14%.

Severe Disparities

Although the Home Office and NPCC declined to specify what setting is currently used, the latest NPL study found the system could generate incorrect matches for Black women nearly a hundred times more often than for white women at specific configurations.

The Home Office commented on these findings: “The testing found that in a specific scenarios the software is has a greater tendency to incorrectly include some population segments in its match reports.”

Balancing Utility and Fairness

Outlining the impact of the brief increase to the system's confidence threshold, the NPCC documents note: “This adjustment significantly reduces the effect of bias across legally safeguarded attributes of ethnicity, generation and gender but had a substantially detrimental effect on operational effectiveness”. The documents further note that forces complained that “a once effective tactic returned results of limited benefit”.

Wider Implementation Proposals

Meanwhile, the government has launched a ten-week consultation on its proposals to widen the use of biometric scanning systems. Policing minister Sarah Jones has described the technology as the “biggest breakthrough since DNA matching”.

Expert and Oversight Concerns

Abimbola Johnson, chair of the advisory panel for the police race action plan, commented: “We observed very little discussion in equality strategy sessions of the facial recognition rollout despite clear relevance with the strategy's goals.

“This disclosure show once again that the pledges to combat discrimination the police has undertaken through the equality initiative are not being translated into wider practice. Independent assessments have cautioned that innovative tools are being rolled out in a landscape where racial disparities, inadequate oversight and poor data collection continue to exist.

“Any use of facial recognition must adhere to strict national standards, be independently scrutinised, and demonstrate it diminishes rather than exacerbates racial disparity.”

Home Office Response

A Home Office spokesperson stated: “The Home Office takes the conclusions of the study with utmost gravity and we have already taken action. A updated software has been externally evaluated and procured, which has demonstrated no measurable discrimination. It will be tested in the coming months and will be subject to evaluation.

“Our priority is protecting the public. This gamechanging technology will support police to put criminals and rapists behind bars. There is officer review in every step of the process and no further action would be pursued without specialist personnel meticulously examining the results.”