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Police forces across the UK effectively campaigned to deploy a face scanning system acknowledged as biased against women, young people, and individuals from ethnic minority groups, following complaints that a more accurate version generated fewer potential suspects.

How the System Works

British police utilize the police national database (PND) to conduct retrospective facial recognition searches. This process entails matching a reference photograph of a person of interest against a database of over 19 million custody photos to find possible hits.

Acknowledged Discrimination

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

“This raises the issue of whether facial recognition only becomes effective if users accept discrimination in ethnicity and gender. Operational ease is a weak argument for disregarding fundamental rights.”

Long-Standing Problem

Official papers show that this bias has been recognized for over twelve months. Furthermore, police forces lobbied to reverse an initial decision that was designed to address the problem.

Police bosses were informed of the algorithmic discrimination in late 2024. The government-ordered NPL review found the system was had a higher probability to produce false positives for photos of females, individuals of Black ethnicity, and those under 40 years old.

A Policy U-Turn

In reaction, the National Police Chiefs’ Council (NPCC) mandated that the confidence threshold required for potential matches be increased to a point where the bias was significantly reduced.

However, this directive was reversed the next month following complaints from police that the adjusted system was generating fewer “investigative leads”. NPCC documents indicate the stricter setting cut the proportion of searches that yielded potential matches from over half to a mere under 15%.

Profound Inequalities

Although the authorities refused to say what threshold is currently used, the recent independent review found the system could produce incorrect matches for Black women almost 100 times more frequently than for Caucasian women at certain settings.

The Home Office stated on these findings: “Our evaluation identified that in a specific scenarios the software is more likely to incorrectly include some demographic groups in its search results.”

Balancing Utility and Fairness

Describing the effect of the temporary raise to the system's confidence threshold, the NPCC documents note: “This adjustment greatly lessens the effect of discrimination across protected characteristics of ethnicity, generation and gender but had a significant negative impact on operational effectiveness”. The papers further note that forces complained that “a previously useful tool returned outcomes of limited benefit”.

Broader Rollout Plans

Meanwhile, the UK administration has launched a ten-week consultation on its plans to expand the use of facial recognition technology. Policing minister Sarah Jones has described the tool as the “most significant advance since genetic fingerprinting”.

Expert and Oversight Concerns

Abimbola Johnson, chair of the independent scrutiny and oversight board for the police race action plan, commented: “We observed very little discussion in race action plan meetings of the technology deployment despite clear relevance with the plan’s concerns.

“This disclosure show once again that the pledges to combat discrimination the police has undertaken via the race action plan are failing to be integrated into broader operations. Our reports have cautioned that new technologies are being implemented in a context where ethnic inequalities, inadequate oversight and poor data collection continue to exist.

“All deployment of this technology must adhere to strict national standards, be independently scrutinised, 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 seriously 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 evaluation.

“Our priority is protecting the public. This revolutionary tool will support police to put criminals and rapists behind bars. There is human involvement in every step of the procedure and no arrest or charge would be pursued without trained officers meticulously examining the output.”