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Law enforcement agencies across the United Kingdom successfully lobbied to deploy a face scanning system acknowledged as biased against females, young people, and members of ethnic minority groups, following complaints that a more accurate version produced fewer potential suspects.

The Technology in Practice

British police use the police national database (PND) to carry out retrospective facial recognition searches. This procedure involves matching a “probe image” of a person of interest against a repository of more than 19 million mugshots to identify possible hits.

Admitted Bias

The Home Office conceded last week that the system was biased. This admission followed a study by the National Physical Laboratory (NPL) determined it misidentified Black and Asian people and women at significantly higher rates than Caucasian males. The ministry 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 gender. Convenience is a weak argument for disregarding basic freedoms.”

Long-Standing Problem

Official papers show that this bias has been recognized for over twelve months. Furthermore, police forces lobbied to reverse an initial decision that was designed to mitigate the problem.

Senior officers were notified of the algorithmic discrimination in late 2024. The government-ordered NPL review found the system was more likely to produce false positives for photos of women, individuals of Black ethnicity, and those aged 40 and under.

A Reversed Decision

In reaction, the national police leadership body ordered that the confidence threshold required for potential matches be increased to a point where the disparity was greatly diminished.

However, this directive was overturned the following month following complaints from police that the modified technology was generating a lower number of “useful lines of inquiry”. NPCC documents indicate the higher threshold cut the proportion of searches resulting in possible identifications from 56% to a mere under 15%.

Severe Disparities

Although the Home Office and NPCC refused to say what setting is now in operation, the latest independent review discovered the system could generate incorrect matches for women of Black heritage nearly a hundred times more often than for Caucasian women at certain settings.

The Home Office commented on these results: “The testing found that in a specific scenarios the algorithm is more likely to incorrectly include some population segments in its match reports.”

Balancing Utility and Fairness

Outlining the impact of the temporary raise to the system's confidence threshold, the NPCC documents note: “The change greatly lessens the effect of bias across legally safeguarded attributes 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 returned results of questionable value”.

Broader Rollout Plans

Meanwhile, the UK administration has launched a ten-week public review on its proposals to widen 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

The chair of a police oversight board, chair of the independent scrutiny and oversight board for the national policing equality strategy, commented: “There was very little consideration through equality strategy sessions of the facial recognition rollout despite clear relevance with the strategy's goals.

“These revelations demonstrate once again that the anti-racism commitments policing has undertaken through the equality initiative are failing to be integrated into wider practice. Our reports have warned that new technologies are being rolled out in a landscape where racial disparities, inadequate oversight and faulty information gathering continue to exist.

“Any use of this technology must meet rigorous official guidelines, be independently scrutinised, and demonstrate it diminishes rather than exacerbates ethnic bias.”

Official Statement

A Home Office spokesperson said: “The Home Office treat the conclusions of the report seriously and we have already taken action. A updated software has been externally evaluated and procured, which has no statistically significant bias. It will be tested early next year and will be undergo further assessment.

“The foremost aim is protecting the public. This gamechanging technology will support officers to put criminals and rapists behind bars. There is human involvement in every step of the procedure and no further action would be pursued without specialist personnel carefully reviewing the output.”