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Police forces across the UK effectively campaigned to use a face scanning system known to be biased against females, young people, and individuals from minority ethnic backgrounds, after complaining that a more accurate version produced fewer investigative leads.

How the System Works

British police utilize the national police database to conduct searches using historical face recognition. This procedure entails comparing a “probe image” of a suspect against a repository of over 19 million custody photos to find possible hits.

Admitted Bias

The UK interior ministry admitted last week that the technology was flawed. This admission followed a review by the government's National Physical Laboratory found it incorrectly matched people of Black and Asian heritage and females at significantly higher rates than Caucasian males. The ministry said it “took steps on the findings”.

“This raises the question of whether facial recognition only becomes useful if users tolerate discrimination in race and gender. Convenience is a poor argument for disregarding fundamental rights.”

Known Issue

Official papers show that this discriminatory flaw has been recognized for more than a year. Furthermore, law enforcement argued to overturn an initial decision that was designed to address the problem.

Senior officers were informed of the algorithmic discrimination in September 2024. The government-ordered laboratory study found the system was more likely to suggest false positives for images depicting women, Black people, and those aged 40 and under.

A Reversed Decision

In response, the National Police Chiefs’ Council (NPCC) ordered that the accuracy setting required for possible hits be increased to a point where the disparity was significantly reduced.

However, this decision was reversed the next month after forces complained that the modified technology was producing a lower number of “investigative leads”. NPCC documents show the higher threshold cut the proportion of searches resulting in possible identifications from over half to a mere 14%.

Severe Disparities

Although the authorities refused to say what threshold is now in operation, the recent NPL study found the system could produce false positives for women of Black heritage almost 100 times more frequently than for white women at certain settings.

The Home Office commented on these results: “The testing identified that in a limited set of circumstances the software is more likely to wrongly flag some demographic groups in its search results.”

Operational Effectiveness vs. Bias

Describing the impact of the temporary raise to the system's confidence threshold, the NPCC documents state: “This adjustment greatly lessens the effect of bias across legally safeguarded attributes of ethnicity, age and gender but had a substantially detrimental effect on police efficiency”. The documents further note that forces complained that “a previously useful tool now delivered outcomes of limited benefit”.

Broader Rollout Plans

Meanwhile, the UK administration has opened a two-and-a-half-month public review on its plans to expand the use of facial recognition technology. Policing minister the relevant minister has described the tool as the “most significant advance since DNA matching”.

Criticism from Advisors and Monitors

Abimbola Johnson, chair of the advisory panel for the national policing equality strategy, commented: “We observed scant consideration in equality strategy sessions of the facial recognition rollout despite clear relevance with the strategy's goals.

“This disclosure show once again that the anti-racism commitments the police has made through the equality initiative are failing to be integrated into broader operations. Our reports have cautioned that new technologies are being implemented in a landscape where racial disparities, weak scrutiny and faulty information gathering already persist.

“All deployment of this technology must adhere to strict national standards, be independently scrutinised, and demonstrate it reduces rather than exacerbates racial disparity.”

Home Office Response

A government representative said: “We treat the conclusions of the study seriously and we have already taken action. A updated software has been externally evaluated and acquired, which has demonstrated no measurable discrimination. It will be trialled early next year and will be subject to evaluation.

“Our priority is protecting the public. This revolutionary tool will assist police to apprehend and prosecute offenders. There is officer review in every step of the process and no arrest or charge would be taken without specialist personnel carefully reviewing the output.”