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Police forces across the United Kingdom effectively campaigned to deploy a facial recognition system known to be discriminatory against women, youths, and members of minority ethnic backgrounds, after complaining that a more accurate version generated a reduced number of investigative leads.

How the System Works

UK forces use the police national database (PND) to carry out retrospective facial recognition searches. This process involves matching a “probe image” of a suspect against a repository of over 19 million custody photos to identify possible hits.

Acknowledged Discrimination

The Home Office admitted last week that the technology was biased. This admission followed a study by the government's National Physical Laboratory found it misidentified people of Black and Asian heritage and females at significantly higher rates than white men. The ministry said it “took steps on the findings”.

“This raises the question of whether this technology only becomes useful if users tolerate biases in ethnicity and sex. Convenience is a poor argument for disregarding basic freedoms.”

Known Issue

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

Police bosses were informed of the system's bias in September 2024. The government-ordered laboratory study found the system was more likely to suggest incorrect matches for images depicting females, Black people, and those aged 40 and under.

A Policy U-Turn

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

However, this directive was reversed the following month following complaints from police that the adjusted system was generating fewer “useful lines of inquiry”. Internal records indicate the higher threshold reduced the proportion of searches resulting in possible identifications from 56% to a just under 15%.

Profound Inequalities

Although the authorities refused to say what threshold is currently used, the recent NPL study discovered the system could produce incorrect matches for Black women nearly a hundred times more often than for Caucasian women at specific configurations.

The Home Office commented on these findings: “Our evaluation found that in a limited set of circumstances the algorithm is has a greater tendency to wrongly flag some population segments in its match reports.”

Operational Effectiveness vs. Bias

Describing the impact of the brief increase to the system's accuracy setting, the NPCC documents note: “This adjustment significantly reduces the impact of discrimination across protected characteristics of race, generation and sex but had a substantially detrimental effect on operational effectiveness”. The documents add that police units argued that “a previously useful tool now delivered outcomes of limited benefit”.

Broader Rollout Plans

Meanwhile, the government has launched a ten-week public review on its proposals to expand the use of facial recognition technology. Policing minister the relevant minister 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, said: “We observed scant consideration in equality strategy sessions of the technology deployment even with obvious cross-over with the plan’s concerns.

“This disclosure show yet again that the anti-racism commitments policing has made through the equality initiative are failing to be integrated into wider practice. Independent assessments have cautioned that innovative tools are being rolled out in a landscape where ethnic inequalities, inadequate oversight and faulty information gathering already persist.

“Any use of facial recognition must meet rigorous official guidelines, be subject to external review, and demonstrate it diminishes rather than compounds ethnic bias.”

Home Office Response

A government representative said: “The Home Office treat the findings of the report with utmost gravity and we have implemented changes. A updated software has been independently tested and procured, which has no statistically significant bias. It will be tested early next year and will be undergo evaluation.

“The foremost aim is protecting the public. This gamechanging technology will support 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 specialist personnel meticulously examining the output.”