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Police forces across the UK successfully lobbied to use a face scanning system acknowledged as discriminatory against women, young people, and members of ethnic minority groups, after complaining that a more accurate version produced a reduced number of investigative leads.

How the System Works

UK forces utilize the police national database (PND) to conduct retrospective facial recognition searches. This procedure entails comparing a reference photograph of a suspect against a database of more than 19 million mugshots to identify possible hits.

Acknowledged Discrimination

The Home Office conceded last week that the system was biased. This admission followed a study by the government's National Physical Laboratory determined it incorrectly matched Black and Asian people and women at much greater frequency than white men. The ministry stated it “took steps on the findings”.

“This raises the question of whether this technology only becomes useful if users tolerate biases in ethnicity and gender. Operational ease is a weak argument for overriding fundamental rights.”

Long-Standing Problem

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

Police bosses were notified of the algorithmic discrimination in late 2024. The government-ordered NPL review found the system was had a higher probability to suggest incorrect matches for images depicting women, individuals of Black ethnicity, and those under 40 years old.

A Reversed Decision

In response, the national police leadership body ordered that the confidence threshold required for potential matches be raised to a level where the bias was greatly diminished.

However, this directive was reversed the next month after forces complained that the modified technology was generating fewer “useful lines of inquiry”. NPCC documents indicate the higher threshold cut the number of searches that yielded potential matches from 56% to a mere under 15%.

Severe Disparities

Although the authorities declined to specify what threshold is currently used, the latest independent review found the system could produce false positives for Black women almost 100 times more often than for white women at certain settings.

The ministry commented on these results: “Our evaluation identified that in a limited set of circumstances the software is has a greater tendency to incorrectly include some population segments in its search results.”

Balancing Utility and Fairness

Outlining the effect of the temporary raise to the system's confidence threshold, the NPCC documents note: “The change greatly lessens the impact of discrimination across protected characteristics of race, age and sex but had a substantially detrimental effect on operational effectiveness”. The papers add that police units complained that “a once effective tactic returned outcomes of limited benefit”.

Broader Rollout Plans

Meanwhile, the UK administration has opened a ten-week public review on its plans to expand the use of biometric scanning systems. Policing minister the relevant minister has labeled the technology as the “biggest breakthrough since DNA matching”.

Criticism from Advisors and Monitors

Abimbola Johnson, head of the independent scrutiny and oversight board for the national policing equality strategy, said: “We observed very little discussion through equality strategy sessions of the technology deployment despite clear relevance with the plan’s concerns.

“This disclosure demonstrate yet again that the anti-racism commitments the police has made through the equality initiative are failing to be integrated into wider practice. Our reports have warned that new technologies are being rolled out in a context where racial disparities, weak scrutiny and faulty information gathering already persist.

“Any use of this technology must meet strict national standards, be independently scrutinised, and demonstrate it reduces rather than exacerbates ethnic bias.”

Official Statement

A Home Office spokesperson said: “We treat the conclusions of the study with utmost gravity and we have already taken action. A new algorithm has been independently tested 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 ensuring public safety. This gamechanging technology will assist police to apprehend and prosecute offenders. There is human involvement in every step of the process and no further action would be pursued without trained officers meticulously examining the output.”