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Police forces across the UK successfully lobbied to deploy a face scanning system acknowledged as discriminatory against females, youths, and members of ethnic minority groups, after complaining that a less biased version produced fewer potential suspects.

How the System Works

British police use the national police database 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 identify possible hits.

Admitted Bias

The Home Office admitted last week that the system was biased. This admission came after a review by the National Physical Laboratory (NPL) determined it misidentified Black and Asian people and women at much greater frequency than Caucasian males. The Home Office stated it “took steps on the findings”.

“It prompts the issue of whether this technology only becomes useful if users accept biases in ethnicity and gender. Convenience is a poor argument for overriding basic freedoms.”

Long-Standing Problem

Internal documents show that this bias has been known about for over twelve months. Furthermore, law enforcement argued to overturn an earlier ruling that was designed to mitigate the problem.

Senior officers were informed of the algorithmic discrimination in late 2024. The Home Office-commissioned NPL review found the system was had a higher probability to suggest incorrect matches for photos of women, Black people, and those aged 40 and under.

A Reversed Decision

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

However, this directive was overturned the next month following complaints from police that the adjusted system was generating fewer “investigative leads”. NPCC documents show the stricter setting cut the proportion of queries that yielded possible identifications from over half to a mere under 15%.

Profound Inequalities

Although the Home Office and NPCC refused to say what setting is currently used, the latest independent review discovered the system could generate false positives for Black women nearly a hundred times more frequently than for Caucasian women at specific configurations.

The ministry commented on these findings: “The testing found 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 effect of the temporary raise to the system's confidence threshold, the NPCC documents state: “The change greatly lessens the effect of discrimination across legally safeguarded attributes of race, generation and sex but had a substantially detrimental effect on police efficiency”. The papers add that police units argued that “a once effective tactic now delivered results of questionable value”.

Wider Implementation Proposals

Meanwhile, the government has opened a ten-week consultation on its proposals to widen the use of facial recognition technology. Policing minister Sarah Jones has labeled the technology as the “most significant advance since DNA matching”.

Criticism from Advisors and Monitors

The chair of a police oversight board, chair of the advisory panel for the national policing equality strategy, commented: “There was scant consideration through race action plan meetings of the technology deployment even with clear relevance with the plan’s concerns.

“These revelations show yet again that the anti-racism commitments policing has undertaken via the equality initiative are not being translated into broader operations. Independent assessments have cautioned that new technologies are being rolled out in a context where ethnic inequalities, inadequate oversight and faulty information gathering already persist.

“Any use of facial recognition must adhere to rigorous official guidelines, be independently scrutinised, and demonstrate it diminishes rather than exacerbates ethnic bias.”

Official Statement

A government representative stated: “We treat the findings of the report with utmost gravity and we have implemented changes. A updated software has been independently tested and procured, which has demonstrated no measurable discrimination. It will be tested early next year and will be subject to 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 every step of the procedure and no further action would be taken without trained officers carefully reviewing the results.”