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Police forces across the UK successfully lobbied to deploy a face scanning system acknowledged as biased against women, young people, and members of ethnic minority groups, following complaints that a more accurate version generated a reduced number of investigative leads.

How the System Works

British police use the police national database (PND) to carry out searches using historical face recognition. This procedure entails matching a reference photograph of a person of interest against a repository of more than 19 million custody photos to identify potential matches.

Admitted Bias

The UK interior ministry admitted last week that the technology was biased. This admission followed a study by the government's National Physical Laboratory found it misidentified people of Black and Asian heritage and females at significantly higher rates than white men. The Home Office stated it “had acted on the findings”.

“This raises the issue of whether facial recognition only becomes useful if users tolerate biases in ethnicity and gender. Convenience is a poor argument for overriding basic freedoms.”

Known Issue

Official papers reveal that this bias has been recognized for over twelve months. Furthermore, police forces argued to overturn an initial decision that was intended to address the problem.

Senior officers were notified of the system's bias in late 2024. The Home Office-commissioned laboratory study found the system was had a higher probability to suggest false positives for images depicting females, individuals of Black ethnicity, and those aged 40 and under.

A Policy U-Turn

In reaction, the national police leadership body ordered that the confidence threshold required for possible hits be increased to a point where the bias was significantly reduced.

However, this directive was overturned the next month following complaints from police that the modified technology was generating fewer “useful lines of inquiry”. NPCC documents indicate the higher threshold reduced the number of queries resulting in possible identifications from 56% to a just under 15%.

Profound Inequalities

Although the Home Office and NPCC refused to say what setting is currently used, the recent independent review found the system could produce false positives for women of Black heritage almost 100 times more frequently than for Caucasian women at certain settings.

The Home Office commented on these results: “The testing identified that in a specific scenarios the software is has a greater tendency to wrongly flag some demographic groups in its match reports.”

Balancing Utility and Fairness

Outlining the impact of the brief increase to the system's confidence threshold, the NPCC documents state: “The change significantly reduces the effect of bias across protected characteristics of ethnicity, generation and sex but had a significant negative impact on police efficiency”. The papers further note that forces argued that “a previously useful tool now delivered outcomes of limited benefit”.

Wider Implementation Proposals

Meanwhile, the UK administration has opened a ten-week consultation on its plans to widen the use of facial recognition technology. The minister for police Sarah Jones has described the tool as the “biggest breakthrough since genetic fingerprinting”.

Expert and Oversight Concerns

The chair of a police oversight board, head of the advisory panel for the national policing equality strategy, said: “There was very little discussion in equality strategy sessions of the facial recognition rollout even with clear relevance with the plan’s concerns.

“This disclosure show yet again that the pledges to combat discrimination the police has made through the equality initiative are not being translated into wider practice. Independent assessments have warned that new technologies are being implemented in a context where ethnic inequalities, inadequate oversight and poor data collection continue to exist.

“All deployment of this technology must adhere to rigorous official guidelines, be subject to external review, and demonstrate it diminishes rather than exacerbates ethnic bias.”

Official Statement

A government representative said: “We treat the findings of the report seriously and we have implemented changes. A new algorithm has been independently tested and acquired, which has no statistically significant bias. It will be tested in the coming months and will be subject to further assessment.

“Our priority is ensuring public safety. This gamechanging technology will support police to put criminals and rapists behind bars. There is officer review in every step of the procedure and no further action would be taken without trained officers carefully reviewing the output.”