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Law enforcement agencies across the United Kingdom effectively campaigned to deploy a facial recognition system known to be biased against women, young people, and members of ethnic minority groups, after complaining that a less biased version produced a reduced number of potential suspects.

The Technology in Practice

British police use the national police database to conduct retrospective facial recognition searches. This procedure involves matching a “probe image” of a person of interest against a repository of more than 19 million custody photos to find potential matches.

Admitted Bias

The Home Office admitted last week that the system was biased. This acknowledgment followed a study by the government's National Physical Laboratory found it misidentified people of Black and Asian heritage and women at significantly higher rates than Caucasian males. The ministry stated it “had acted on the findings”.

“This raises the question of whether facial recognition only becomes effective if users accept discrimination in ethnicity and sex. Operational ease is a weak argument for overriding basic freedoms.”

Long-Standing Problem

Official papers reveal that this bias has been recognized for more than a year. Furthermore, police forces argued to overturn an initial decision that was designed to mitigate the problem.

Police bosses were informed of the algorithmic discrimination in late 2024. The government-ordered NPL review concluded the system was more likely to produce false positives for images depicting women, individuals of Black ethnicity, and those under 40 years old.

A Reversed Decision

In response, the National Police Chiefs’ Council (NPCC) ordered that the confidence threshold required for potential matches be raised to a level where the bias was significantly reduced.

However, this directive was overturned the following month following complaints from police that the adjusted system was generating a lower number of “useful lines of inquiry”. Internal records indicate the stricter setting reduced the proportion of searches resulting in possible identifications from over half to a just under 15%.

Severe Disparities

Although the authorities declined to specify what threshold is now in operation, the latest independent review found the system could produce incorrect matches for women of Black heritage nearly a hundred times more often than for white women at certain settings.

The ministry commented on these results: “The testing found that in a limited set of circumstances the algorithm is more likely to incorrectly include some demographic groups in its search results.”

Operational Effectiveness vs. Bias

Outlining the impact of the temporary raise to the system's confidence threshold, the police records note: “The change greatly lessens the effect of discrimination across protected characteristics of ethnicity, generation and gender but had a substantially detrimental effect on police efficiency”. The papers add that forces argued that “a previously useful tool returned results of questionable value”.

Wider Implementation Proposals

Meanwhile, the UK administration has opened a ten-week public review on its proposals to widen the use of facial recognition technology. The minister for police the relevant minister has described the technology as the “biggest breakthrough since genetic fingerprinting”.

Expert and Oversight Concerns

Abimbola Johnson, chair of the advisory panel for the national policing equality strategy, commented: “There was very little discussion in equality strategy sessions of the technology deployment even with obvious cross-over with the plan’s concerns.

“These revelations demonstrate yet again that the pledges to combat discrimination the police has made via the equality initiative are not being translated into broader operations. Our reports have warned that new technologies are being rolled out in a context where ethnic inequalities, weak scrutiny and poor data collection already persist.

“All deployment of facial recognition must adhere to strict national standards, be subject to external review, and prove 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 externally evaluated and acquired, which has no statistically significant bias. It will be trialled early next year and will be subject to further assessment.

“The foremost aim is ensuring public safety. This revolutionary tool will support officers to apprehend and prosecute offenders. There is human involvement in each stage of the procedure and no arrest or charge would be pursued without specialist personnel carefully reviewing the results.”