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Police forces across the UK effectively campaigned to use a face scanning system known to be discriminatory against women, youths, and members of minority ethnic backgrounds, following complaints that a less biased version produced a reduced number of investigative leads.

The Technology in Practice

UK forces use the national police database to carry out searches using historical face recognition. This process entails matching a reference photograph of a suspect against a database of more than 19 million custody photos to find possible hits.

Acknowledged Discrimination

The Home Office conceded last week that the system was biased. This acknowledgment came after a study by the government's National Physical Laboratory determined it misidentified Black and Asian people and females at significantly higher rates than Caucasian males. The ministry stated it “had acted on the findings”.

“It prompts the question of whether facial recognition only becomes useful if users accept discrimination in ethnicity and gender. Convenience is a weak argument for disregarding fundamental rights.”

Long-Standing Problem

Official papers reveal that this bias has been known about for over twelve months. Furthermore, police forces lobbied to reverse an initial decision that was intended to address the problem.

Police bosses were informed of the system's bias in September 2024. The government-ordered laboratory study concluded the system was had a higher probability to produce incorrect matches for images depicting women, Black people, and those aged 40 and under.

A Policy U-Turn

In response, the National Police Chiefs’ Council (NPCC) mandated that the confidence threshold required for possible hits be raised to a level where the disparity was significantly reduced.

However, this directive was overturned the next 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 queries resulting in potential matches from over half to a mere 14%.

Severe Disparities

Although the Home Office and NPCC declined to specify what setting is now in operation, the recent independent review found the system could produce incorrect matches for women of Black heritage nearly a hundred times more frequently than for Caucasian women at specific configurations.

The ministry 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 search results.”

Balancing Utility and Fairness

Describing the impact of the brief increase to the system's confidence threshold, the NPCC documents state: “This adjustment significantly reduces the effect of discrimination across protected characteristics of race, 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 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 the relevant minister has described the technology as the “biggest breakthrough since DNA matching”.

Criticism from Advisors and Monitors

Abimbola Johnson, chair of the advisory panel for the national policing equality strategy, commented: “We observed very little discussion in race action plan meetings of the technology deployment despite clear relevance with the plan’s concerns.

“These revelations show yet again that the anti-racism commitments the police has made via the equality initiative are not being translated into broader operations. Our reports have warned that innovative tools are being implemented in a landscape where ethnic inequalities, inadequate oversight and poor data collection continue to exist.

“All deployment of this technology must meet strict national standards, be independently scrutinised, and demonstrate it diminishes rather than exacerbates ethnic bias.”

Official Statement

A government representative stated: “We treat the conclusions of the report with utmost gravity and we have implemented changes. A new algorithm has been externally evaluated and acquired, which has no statistically significant bias. It will be tested in the coming months and will be undergo evaluation.

“The foremost aim is protecting the public. This gamechanging technology will support police to apprehend and prosecute offenders. There is officer review in each stage of the process and no further action would be pursued without specialist personnel meticulously examining the results.”