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Law enforcement agencies across the UK effectively campaigned to use a face scanning system known to be discriminatory 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 use the national police database to conduct retrospective facial recognition searches. This process involves comparing a “probe image” of a suspect against a repository of over 19 million mugshots to find possible hits.

Admitted Bias

The Home Office admitted last week that the system was flawed. This admission followed a review by the National Physical Laboratory (NPL) determined it misidentified Black and Asian people and females at significantly higher rates than white men. The Home Office stated it “had acted on the findings”.

“It prompts the issue of whether this technology only becomes effective if users tolerate biases in ethnicity and sex. Operational ease is a weak argument for overriding basic freedoms.”

Known Issue

Official papers show that this discriminatory flaw has been recognized for over twelve months. Furthermore, law enforcement argued to overturn an initial decision that was designed to mitigate the problem.

Senior officers were notified of the system's bias in September 2024. The Home Office-commissioned NPL review concluded the system was had a higher probability to produce incorrect matches for images depicting females, Black people, and those aged 40 and under.

A Policy U-Turn

In response, the National Police Chiefs’ Council (NPCC) ordered that the accuracy setting required for possible hits be raised to a level where the bias was greatly diminished.

However, this directive was reversed the following month after forces complained that the modified technology was producing a lower number of “useful lines of inquiry”. NPCC documents indicate the stricter setting reduced the number of queries resulting in possible identifications from over half to a mere under 15%.

Profound Inequalities

Although the authorities refused to say what threshold is now in operation, the latest NPL study found the system could generate incorrect matches for Black women almost 100 times more often than for white women at specific configurations.

The ministry commented on these results: “Our evaluation identified that in a limited set of circumstances the algorithm is more likely to incorrectly include some population segments in its search results.”

Balancing Utility and Fairness

Outlining the impact of the brief increase to the system's accuracy setting, the NPCC documents note: “The change significantly reduces the effect of bias across legally safeguarded attributes of ethnicity, age and sex but had a significant negative impact on operational effectiveness”. The documents add that police units argued that “a previously useful tool now delivered outcomes of limited benefit”.

Broader Rollout Plans

Meanwhile, the UK administration has launched a ten-week consultation on its proposals to expand the use of biometric scanning systems. Policing minister Sarah Jones has labeled the tool as the “biggest breakthrough since genetic fingerprinting”.

Criticism from Advisors and Monitors

Abimbola Johnson, head of the advisory panel for the police race action plan, commented: “We observed scant consideration in race action plan meetings of the facial recognition rollout despite obvious cross-over with the plan’s concerns.

“These revelations show once 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 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 facial recognition must adhere to rigorous official guidelines, be subject to external review, and prove it diminishes rather than exacerbates ethnic bias.”

Official Statement

A government representative stated: “We treat the conclusions of the report seriously and we have implemented changes. A updated software has been externally evaluated and acquired, which has no statistically significant bias. It will be tested in the coming months and will be subject to evaluation.

“The foremost aim is protecting the public. This gamechanging technology will support officers to apprehend and prosecute offenders. There is officer review in each stage of the process and no further action would be taken without trained officers carefully reviewing the results.”