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Police forces across the United Kingdom successfully lobbied to use a facial recognition system known to be biased against women, young people, and individuals from ethnic minority groups, following complaints that a more accurate version generated a reduced number of investigative leads.

How the System Works

British police use the police national database (PND) to carry out searches using historical face recognition. This process entails matching a “probe image” of a suspect against a database of more than 19 million custody photos to find potential matches.

Admitted Bias

The Home Office admitted last week that the system was flawed. This acknowledgment came after a study by the government's National Physical Laboratory determined it misidentified people of Black and Asian heritage and females at much greater frequency than Caucasian males. The Home Office stated it “took steps on the findings”.

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

Long-Standing Problem

Internal documents show that this bias has been recognized for more than a year. Furthermore, law enforcement argued to overturn an initial decision that was intended to address the problem.

Police bosses were informed of the system's bias in late 2024. The Home Office-commissioned laboratory study concluded the system was more likely to suggest false positives for photos of women, Black people, 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 overturned the next month after forces complained that the modified technology was producing a lower number of “useful lines of inquiry”. Internal records show the stricter setting reduced the proportion of searches that yielded possible identifications from over half to a mere 14%.

Profound Inequalities

Although the authorities declined to specify what setting is currently used, the latest NPL study discovered the system could produce incorrect matches for women of Black heritage almost 100 times more often than for Caucasian women at certain settings.

The Home Office stated on these results: “The testing identified that in a specific scenarios the algorithm is has a greater tendency to incorrectly include some population segments in its match reports.”

Operational Effectiveness vs. Bias

Describing the impact of the brief increase to the system's confidence threshold, the police records state: “The change greatly lessens the impact of bias across protected characteristics of ethnicity, age and gender but had a substantially detrimental effect on operational effectiveness”. The papers add that forces complained that “a previously useful tool now delivered results of questionable value”.

Wider Implementation Proposals

Meanwhile, the UK administration has opened a ten-week public review on its plans to expand the use of biometric scanning systems. The minister for police Sarah Jones has described the technology as the “most significant advance since DNA matching”.

Expert and Oversight Concerns

The chair of a police oversight board, chair of the independent scrutiny and oversight board for the police race action plan, said: “We observed scant discussion through equality strategy sessions of the facial recognition rollout despite clear relevance with the plan’s concerns.

“This disclosure show yet again that the pledges to combat discrimination policing has made through the race action plan are failing to be integrated into broader operations. Our reports have warned that innovative tools are being rolled out in a context where racial disparities, weak scrutiny and faulty information gathering continue to exist.

“Any use of this technology must adhere to strict national standards, be subject to external review, and prove it diminishes rather than exacerbates ethnic bias.”

Home Office Response

A government representative stated: “The Home Office treat the conclusions of the report with utmost gravity and we have implemented changes. A updated software has been externally evaluated and acquired, which has no statistically significant bias. It will be tested early next year and will be subject to further assessment.

“The foremost aim is ensuring public safety. This gamechanging technology will support officers to apprehend and prosecute offenders. There is officer review in every step of the procedure and no further action would be taken without trained officers carefully reviewing the output.”