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Law enforcement agencies across the UK effectively campaigned to use a facial recognition system known to be discriminatory against females, young people, and members of minority ethnic backgrounds, after complaining that a more accurate version generated fewer potential suspects.

How the System Works

British police utilize the police national database (PND) to conduct searches using historical face recognition. This procedure involves matching a “probe image” of a suspect against a repository of more than 19 million custody photos to find potential matches.

Admitted Bias

The UK interior ministry admitted last week that the system was flawed. This admission came after a study by the National Physical Laboratory (NPL) determined it incorrectly matched Black and Asian people and women at much greater frequency than Caucasian males. The ministry stated it “took steps on the findings”.

“It prompts the issue of whether this technology only becomes useful if users accept biases in ethnicity and gender. Operational ease is a poor argument for overriding fundamental rights.”

Known Issue

Internal documents reveal that this bias has been known about for over twelve months. Furthermore, police forces argued to overturn an earlier ruling that was designed to address the problem.

Police bosses were informed of the algorithmic discrimination in late 2024. The Home Office-commissioned NPL review concluded the system was more likely to suggest incorrect matches for photos of women, Black people, and those aged 40 and under.

A Reversed Decision

In reaction, the national police leadership body ordered that the confidence threshold required for possible hits be increased to a point where the bias was significantly reduced.

However, this directive was overturned the next month following complaints from police that the modified technology was producing 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 14%.

Severe Disparities

Although the authorities declined to specify what setting is currently used, the recent 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: “Our evaluation found that in a limited set of circumstances the software is more likely to wrongly flag some demographic groups in its match reports.”

Balancing Utility and Fairness

Outlining the impact of the brief increase to the system's accuracy setting, the NPCC documents note: “The change greatly lessens the impact of bias across protected characteristics of ethnicity, age and sex but had a substantially detrimental effect on police efficiency”. The papers further note that forces argued that “a previously useful tool now delivered outcomes of limited benefit”.

Wider Implementation Proposals

Meanwhile, the UK administration has opened a ten-week public review on its proposals to expand the use of facial recognition technology. Policing minister Sarah Jones has labeled the technology as the “most significant advance since DNA matching”.

Expert and Oversight Concerns

Abimbola Johnson, chair of the advisory panel for the police race action plan, said: “We observed scant discussion through equality strategy sessions of the facial recognition rollout even with obvious cross-over with the plan’s concerns.

“This disclosure demonstrate yet again that the pledges to combat discrimination policing has made via the race action plan are failing to be integrated into wider practice. Our reports have warned that innovative tools are being implemented in a landscape where ethnic inequalities, inadequate oversight and faulty information gathering continue to exist.

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

Official Statement

A government representative said: “The Home Office takes the conclusions of the study with utmost gravity and we have implemented changes. A updated software has been independently tested and acquired, which has no statistically significant bias. It will be trialled in the coming months and will be subject to evaluation.

“Our priority is protecting the public. This gamechanging technology will assist police to put criminals and rapists behind bars. There is officer review in each stage of the process and no arrest or charge would be pursued without trained officers carefully reviewing the results.”