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Police forces across the UK successfully lobbied to use a face scanning system known to be discriminatory against women, youths, and members of minority ethnic backgrounds, following complaints that a more accurate version generated fewer investigative leads.

How the System Works

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

Acknowledged Discrimination

The UK interior ministry admitted last week that the system was flawed. This acknowledgment came after a study by the government's National Physical Laboratory found it incorrectly matched Black and Asian people and women at much greater frequency than white men. The Home Office stated it “took steps on the findings”.

“This raises the issue of whether this technology only becomes useful if users tolerate biases in race and gender. Operational ease is a weak argument for overriding basic freedoms.”

Long-Standing Problem

Official papers reveal that this discriminatory flaw has been known about for more than a year. Furthermore, police forces lobbied to reverse an earlier ruling that was designed to address the problem.

Senior officers were informed of the system's bias in late 2024. The government-ordered NPL review concluded the system was more likely to produce incorrect matches for photos of women, individuals of Black ethnicity, and those aged 40 and under.

A Reversed Decision

In response, the national police leadership body mandated that the accuracy setting required for potential matches be raised to a level where the disparity was greatly diminished.

However, this directive was reversed the next month following complaints from police that the adjusted system was generating fewer “investigative leads”. NPCC documents show the stricter setting reduced the proportion of queries resulting in potential matches from 56% to a mere under 15%.

Profound Inequalities

Although the authorities refused to say what threshold is now in operation, the latest independent review found the system could produce false positives for Black women nearly a hundred times more frequently than for Caucasian women at certain settings.

The ministry stated on these results: “Our evaluation found that in a limited set of circumstances 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 police records note: “This adjustment significantly reduces the impact of discrimination across protected characteristics of race, generation and gender but had a significant negative impact on police efficiency”. The papers further note that forces complained that “a previously useful tool returned results of limited benefit”.

Broader Rollout Plans

Meanwhile, the government has opened a two-and-a-half-month public review on its plans to expand the use of facial recognition technology. The minister for police the relevant minister has described the tool as the “most significant advance since DNA matching”.

Expert and Oversight Concerns

Abimbola Johnson, head of the advisory panel for the police race action plan, said: “There was scant discussion through race action plan meetings of the technology deployment even with obvious cross-over with the plan’s concerns.

“This disclosure demonstrate once again that the anti-racism commitments the police has made through the race action plan are failing to be integrated into broader operations. Independent assessments have cautioned that innovative tools are being implemented in a landscape where racial disparities, weak scrutiny and faulty information gathering continue to exist.

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

Official Statement

A Home Office spokesperson said: “The Home Office takes the findings of the report seriously and we have implemented changes. A new algorithm has been externally evaluated and procured, which has no statistically significant bias. It will be trialled early next year and will be undergo further assessment.

“Our priority is ensuring public safety. This gamechanging technology will support officers to apprehend and prosecute offenders. There is human involvement in each stage of the procedure and no further action would be pursued without trained officers meticulously examining the output.”