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Law enforcement agencies across the United Kingdom effectively campaigned to use a facial recognition system acknowledged as biased against women, youths, and members of minority ethnic backgrounds, after complaining that a more accurate version produced a reduced number of potential suspects.

How the System Works

British police use the national police database to conduct searches using historical face recognition. This process involves comparing a “probe image” of a suspect against a database of over 19 million mugshots to find possible hits.

Admitted Bias

The Home Office admitted last week that the technology was biased. This admission came after a study by the government's National Physical Laboratory determined it incorrectly matched people of Black and Asian heritage and females at significantly higher rates than Caucasian males. The Home Office stated it “took steps on the findings”.

“This raises the issue of whether this technology only becomes useful if users accept biases in race and gender. Operational ease is a poor argument for disregarding fundamental rights.”

Known Issue

Internal documents show that this discriminatory flaw has been recognized for more than a year. Furthermore, law enforcement argued to overturn an earlier ruling that was intended to mitigate the problem.

Police bosses were informed of the system's bias in late 2024. The government-ordered laboratory study concluded the system was had a higher probability to suggest false positives for images depicting women, Black people, and those under 40 years old.

A Policy U-Turn

In response, the National Police Chiefs’ Council (NPCC) mandated that the accuracy setting required for potential matches be raised to a point where the bias was significantly reduced.

However, this directive was overturned the next month following complaints from police that the adjusted system was generating fewer “investigative leads”. NPCC documents indicate the higher threshold cut the number of queries resulting in potential matches from 56% to a mere 14%.

Profound Inequalities

Although the authorities refused to say what threshold is now in operation, the recent independent review found the system could generate false positives for Black women almost 100 times more often than for Caucasian women at certain settings.

The Home Office stated on these results: “Our evaluation found that in a specific scenarios the software is more likely to wrongly flag some demographic groups in its match reports.”

Operational Effectiveness vs. Bias

Outlining the effect of the temporary raise to the system's confidence threshold, the NPCC documents note: “The change significantly reduces the impact of bias across legally safeguarded attributes of ethnicity, age and sex but had a substantially detrimental effect on operational effectiveness”. The documents add that forces complained that “a previously useful tool now delivered outcomes of questionable value”.

Broader Rollout Plans

Meanwhile, the government has launched a two-and-a-half-month public review on its plans to expand the use of biometric scanning systems. The minister for police the relevant minister has described the tool as the “most significant advance since genetic fingerprinting”.

Expert and Oversight Concerns

Abimbola Johnson, head of the independent scrutiny and oversight board for the national policing equality strategy, said: “We observed scant discussion in equality strategy sessions of the technology deployment despite clear relevance with the strategy's goals.

“These revelations show once again that the anti-racism commitments the police has undertaken through the equality initiative are failing to be integrated into broader operations. Independent assessments have cautioned that innovative tools are being implemented in a landscape where ethnic inequalities, inadequate oversight and poor data collection already persist.

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

Official Statement

A government representative said: “We treat the findings of the study seriously and we have implemented changes. A updated software 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 further assessment.

“Our priority is ensuring public safety. This revolutionary tool will assist officers to apprehend and prosecute offenders. There is officer review in every step of the procedure and no arrest or charge would be pursued without specialist personnel meticulously examining the results.”