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Police forces across the UK effectively campaigned to deploy a facial recognition system known to be biased against women, young people, and individuals from minority ethnic backgrounds, after complaining that a less biased version generated a reduced number of potential suspects.

How the System Works

British police utilize the national police database to conduct searches using historical face recognition. This process involves matching a reference photograph of a suspect against a repository of over 19 million custody photos to identify possible hits.

Admitted Bias

The Home Office admitted last week that the system was biased. This acknowledgment 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 Caucasian males. The ministry said it “took steps on the findings”.

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

Long-Standing Problem

Internal documents show that this bias has been recognized for over twelve months. Furthermore, law enforcement argued to overturn an earlier ruling that was intended to address the problem.

Senior officers were notified of the system's bias in late 2024. The Home Office-commissioned NPL review found the system was more likely to suggest incorrect matches for photos of women, individuals of Black ethnicity, and those aged 40 and under.

A Reversed Decision

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

However, this decision was overturned the following month after forces complained that the modified technology was producing a lower number of “useful lines of inquiry”. Internal records indicate the higher threshold reduced the proportion of queries that yielded possible identifications from over half to a just 14%.

Severe Disparities

Although the Home Office and NPCC refused to say what threshold is currently used, the latest NPL study found the system could produce false positives for Black women almost 100 times more frequently than for white women at specific configurations.

The ministry stated on these findings: “The testing found that in a limited set of circumstances the algorithm is more likely to incorrectly include some population segments in its search results.”

Operational Effectiveness vs. Bias

Describing the impact of the brief increase to the system's confidence threshold, the police records state: “The change greatly lessens the impact of bias across protected characteristics of race, age and sex but had a substantially detrimental effect on police efficiency”. The papers further note that forces complained that “a once effective tactic returned outcomes of questionable value”.

Broader Rollout Plans

Meanwhile, the UK administration has opened a two-and-a-half-month public review on its plans to widen the use of biometric scanning systems. Policing minister the relevant minister has described the tool as the “most significant advance since DNA matching”.

Expert and Oversight Concerns

Abimbola Johnson, head of the independent scrutiny and oversight board for the police race action plan, commented: “There was very little discussion in equality strategy sessions of the technology deployment even with obvious cross-over with the strategy's goals.

“These revelations show once again that the pledges to combat discrimination policing has undertaken through the race action plan are failing to be integrated into wider practice. Our reports have warned that new technologies are being rolled out in a context where ethnic inequalities, weak scrutiny and faulty information gathering continue to exist.

“All deployment of this technology must meet strict national standards, be subject to external review, and prove it diminishes rather than compounds ethnic bias.”

Home Office Response

A government representative said: “We takes the conclusions of the report seriously and we have already taken action. A updated software has been externally evaluated and acquired, which has demonstrated no measurable discrimination. It will be trialled in the coming months and will be subject to evaluation.

“The foremost aim is protecting the public. This revolutionary tool will support police to apprehend and prosecute offenders. There is human involvement in each stage of the procedure and no arrest or charge would be taken without specialist personnel carefully reviewing the output.”