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Police forces across the UK effectively campaigned to deploy a facial recognition system acknowledged as biased against women, young people, and members of 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 carry out searches using historical face recognition. This procedure involves comparing a “probe image” of a suspect against a database of more than 19 million custody photos to identify possible hits.

Acknowledged Discrimination

The UK interior ministry admitted last week that the technology was flawed. This acknowledgment followed a study by the National Physical Laboratory (NPL) found it incorrectly matched Black and Asian people and females at much greater frequency than white men. The ministry said it “had acted on the findings”.

“This raises the issue of whether this technology only becomes effective if users tolerate discrimination in race and sex. Convenience is a poor argument for overriding fundamental rights.”

Known Issue

Official papers show that this discriminatory flaw has been recognized for over twelve months. Furthermore, police forces argued to overturn an earlier ruling that was intended to address the problem.

Police bosses were notified of the system's bias in September 2024. The Home Office-commissioned laboratory study found the system was more likely to produce false positives for images depicting women, individuals of Black ethnicity, and those under 40 years old.

A Policy U-Turn

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

However, this decision was reversed the following month following complaints from police that the adjusted system was generating fewer “useful lines of inquiry”. NPCC documents indicate the higher threshold cut the number of searches that yielded possible identifications from over half to a mere under 15%.

Severe Disparities

Although the authorities refused to say what threshold is currently used, the recent independent review found the system could produce false positives for women of Black heritage almost 100 times more often than for Caucasian women at specific configurations.

The Home Office stated on these results: “The testing identified that in a specific scenarios the algorithm is more likely to incorrectly include some demographic groups in its search results.”

Operational Effectiveness vs. Bias

Outlining the impact of the brief increase to the system's accuracy setting, the police records note: “The change significantly reduces the effect of bias across legally safeguarded attributes of race, generation and gender but had a significant negative impact on operational effectiveness”. The documents add that police units argued that “a once effective tactic returned results of limited benefit”.

Broader Rollout Plans

Meanwhile, the UK administration has opened a two-and-a-half-month public review on its proposals to widen the use of biometric scanning systems. Policing minister the relevant minister has labeled the tool as the “biggest breakthrough since genetic fingerprinting”.

Expert and Oversight Concerns

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

“These revelations show yet again that the pledges to combat discrimination policing has made via the equality initiative are not being translated into wider practice. Independent assessments have warned that new technologies are being implemented in a landscape where ethnic inequalities, weak scrutiny and faulty information gathering already persist.

“Any use of facial recognition must meet strict national standards, be subject to external review, and demonstrate it reduces rather than compounds ethnic bias.”

Official Statement

A Home Office spokesperson stated: “We treat the conclusions of the study seriously and we have implemented changes. A new algorithm has been externally evaluated and procured, which has demonstrated no measurable discrimination. It will be trialled early next year and will be undergo further assessment.

“Our priority is ensuring public safety. This revolutionary tool will assist officers to apprehend and prosecute offenders. There is human involvement in each stage of the process and no arrest or charge would be taken without trained officers meticulously examining the results.”