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Police forces across the United Kingdom successfully lobbied to deploy a face scanning system known to be biased against women, young people, and members of minority ethnic backgrounds, after complaining that a more accurate version generated fewer investigative leads.

How the System Works

British police utilize the police national database (PND) to carry out retrospective facial recognition searches. This process involves matching a reference photograph of a suspect against a repository of more than 19 million mugshots to identify possible hits.

Acknowledged Discrimination

The Home Office conceded last week that the technology was flawed. This acknowledgment followed a study by the National Physical Laboratory (NPL) determined it incorrectly matched Black and Asian people and females at significantly higher rates than white men. The Home Office stated it “took steps on the findings”.

“It prompts the issue of whether facial recognition only becomes effective if users tolerate discrimination in ethnicity and sex. Operational ease is a poor argument for disregarding basic freedoms.”

Long-Standing Problem

Internal documents show that this bias has been known about for more than a year. Furthermore, police forces argued to overturn an earlier ruling that was intended to mitigate the problem.

Police bosses were informed of the system's bias in September 2024. The government-ordered NPL review found the system was had a higher probability to suggest incorrect matches for photos of females, Black people, and those aged 40 and under.

A Policy U-Turn

In reaction, the national police leadership body ordered that the accuracy setting required for possible hits be raised to a point where the disparity was significantly reduced.

However, this directive was overturned the following month after forces complained that the adjusted system was producing a lower number of “investigative leads”. NPCC documents show the stricter setting cut the number of queries resulting in potential matches from over half to a mere under 15%.

Severe Disparities

Although the Home Office and NPCC refused to say what setting is now in operation, the recent independent review found the system could generate false positives for women of Black heritage nearly a hundred times more frequently than for Caucasian women at certain settings.

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

Balancing Utility and Fairness

Describing the effect of the temporary raise to the system's accuracy setting, the NPCC documents state: “The change significantly reduces the effect of bias across protected characteristics of race, generation and sex but had a substantially detrimental effect on police efficiency”. The papers further note that forces argued that “a once effective tactic returned results of limited benefit”.

Wider Implementation Proposals

Meanwhile, the government has launched a ten-week consultation on its proposals to expand the use of biometric scanning systems. Policing minister the relevant minister has described the technology as the “most significant advance since DNA matching”.

Expert and Oversight Concerns

The chair of a police oversight board, head of the advisory panel for the police race action plan, commented: “We observed scant consideration through race action plan meetings of the technology deployment despite obvious cross-over with the strategy's goals.

“These revelations demonstrate yet again that the anti-racism commitments the police has made through the race action plan are failing to be integrated into wider practice. Our reports have cautioned that innovative tools are being implemented in a context where ethnic inequalities, inadequate oversight and poor data collection already persist.

“Any use of facial recognition must meet strict national standards, be subject to external review, and demonstrate it reduces rather than compounds ethnic bias.”

Official Statement

A government representative said: “We takes the findings of the study seriously 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 undergo further assessment.

“The foremost aim is protecting the public. This revolutionary tool will support officers to apprehend and prosecute offenders. There is human involvement in every step of the process and no further action would be taken without trained officers carefully reviewing the results.”