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Police forces across the United Kingdom effectively campaigned to use a facial recognition system acknowledged as biased against women, youths, and individuals from minority ethnic backgrounds, following complaints that a less biased version generated fewer potential suspects.

The Technology in Practice

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

Admitted Bias

The Home Office conceded last week that the technology was biased. This acknowledgment followed a study by the National Physical Laboratory (NPL) determined it incorrectly matched people of Black and Asian heritage and females at much greater frequency than Caucasian males. The Home Office stated it “took steps on the findings”.

“This raises the issue of whether facial recognition only becomes effective if users tolerate biases in race and gender. Convenience is a poor argument for disregarding fundamental rights.”

Known Issue

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

Senior officers were notified of the algorithmic discrimination in late 2024. The Home Office-commissioned laboratory study concluded the system was had a higher probability to produce false positives for photos of females, Black people, and those aged 40 and under.

A Reversed Decision

In response, the national police leadership body mandated that the accuracy setting required for possible hits be increased to a point where the disparity was significantly reduced.

However, this decision was reversed the following month following complaints from police that the adjusted system was generating fewer “investigative leads”. NPCC documents indicate the stricter setting reduced the number of queries resulting in potential matches from over half to a just under 15%.

Profound Inequalities

Although the authorities declined to specify what threshold is currently used, the latest independent review found the system could generate incorrect matches for Black women almost 100 times more often than for Caucasian women at specific configurations.

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

Operational Effectiveness vs. Bias

Describing the impact of the temporary raise to the system's confidence threshold, the NPCC documents state: “This adjustment greatly lessens the effect of bias across legally safeguarded attributes of race, age and gender but had a substantially detrimental effect on police efficiency”. The documents further note that police units argued that “a once effective tactic returned results of questionable value”.

Broader Rollout Plans

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 Sarah Jones has described the tool as the “biggest breakthrough since genetic fingerprinting”.

Expert and Oversight Concerns

The chair of a police oversight board, head 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 plan’s concerns.

“This disclosure show yet again that the anti-racism commitments the police has made via the equality initiative are failing to be integrated into broader operations. Independent assessments have warned that innovative tools are being rolled out in a context where racial disparities, weak scrutiny and poor data collection already persist.

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

Official Statement

A Home Office spokesperson stated: “We treat the conclusions of the report seriously and we have implemented changes. A updated software has been externally evaluated and procured, which has no statistically significant bias. It will be tested in the coming months and will be undergo evaluation.

“Our priority is protecting the public. This gamechanging technology will assist officers to apprehend and prosecute offenders. There is officer review in every step of the procedure and no further action would be pursued without trained officers meticulously examining the output.”