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Police forces across the UK successfully lobbied to deploy a facial recognition system known to be discriminatory against women, young people, and individuals from minority ethnic backgrounds, following complaints that a less biased version produced a reduced number of potential suspects.

How the System Works

British police utilize the police national database (PND) to conduct searches using historical face recognition. This process involves matching a reference photograph of a person of interest against a database of over 19 million mugshots to find potential matches.

Admitted Bias

The UK interior ministry conceded last week that the system was biased. This admission came after a study by the government's National Physical Laboratory determined it misidentified Black and Asian people and women at much greater frequency than Caucasian males. The ministry said it “had acted on the findings”.

“This raises the question of whether this technology only becomes useful if users tolerate biases in race and sex. Convenience is a weak argument for disregarding fundamental rights.”

Known Issue

Internal documents reveal that this discriminatory flaw has been known about for more than a year. Furthermore, police forces argued to overturn an initial decision that was designed to address the problem.

Senior officers were informed of the system's bias in September 2024. The Home Office-commissioned NPL review concluded the system was had a higher probability to suggest incorrect matches for photos of females, Black people, and those under 40 years old.

A Reversed Decision

In reaction, the National Police Chiefs’ Council (NPCC) mandated that the accuracy setting required for possible hits be increased to a point where the bias was greatly diminished.

However, this decision was reversed the next month following complaints from police that the adjusted system was generating fewer “investigative leads”. Internal records show the higher threshold cut the number of searches resulting in possible identifications from 56% to a just 14%.

Profound Inequalities

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

The Home Office commented on these findings: “The testing found that in a limited set of circumstances the software is has a greater tendency to incorrectly include some demographic groups in its search results.”

Operational Effectiveness vs. Bias

Outlining the effect of the brief increase to the system's accuracy setting, the NPCC documents state: “This adjustment greatly lessens the impact of discrimination across protected characteristics of ethnicity, generation and gender but had a substantially detrimental effect on police efficiency”. The documents further note that police units argued that “a once effective tactic now delivered outcomes of limited benefit”.

Wider Implementation Proposals

Meanwhile, the government has launched a two-and-a-half-month public review on its plans to widen the use of facial recognition technology. Policing minister the relevant minister has described the technology as the “biggest breakthrough since DNA matching”.

Criticism from Advisors and Monitors

The chair of a police oversight board, chair of the independent scrutiny and oversight board for the national policing equality strategy, said: “We observed very little consideration in race action plan meetings of the technology deployment despite obvious cross-over with the strategy's goals.

“This disclosure show yet again that the anti-racism commitments policing has undertaken via the equality initiative are not being translated into wider practice. Our reports have cautioned that innovative tools are being rolled out in a landscape where racial disparities, inadequate oversight and poor data collection continue to exist.

“All deployment of this technology must meet rigorous official guidelines, be subject to external review, and prove it diminishes rather than compounds racial disparity.”

Home Office Response

A government representative stated: “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 demonstrated no measurable discrimination. It will be trialled early next year and will be undergo further assessment.

“Our priority is ensuring public safety. This gamechanging technology will assist police to put criminals and rapists behind bars. There is human involvement in each stage of the procedure and no further action would be taken without specialist personnel meticulously examining the results.”