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Law enforcement agencies across the UK effectively campaigned to deploy a face scanning system acknowledged as biased against women, youths, and individuals from ethnic minority groups, after complaining that a more accurate version produced fewer potential suspects.

The Technology in Practice

UK forces utilize the police national database (PND) to conduct searches using historical face recognition. This process entails comparing a “probe image” of a person of interest against a database of more than 19 million mugshots to identify potential matches.

Admitted Bias

The Home Office conceded last week that the system was biased. This acknowledgment followed a study by the National Physical Laboratory (NPL) found it incorrectly matched people of Black and Asian heritage and females at much greater frequency than Caucasian males. The ministry said it “took steps on the findings”.

“This raises the question of whether facial recognition only becomes effective if users accept biases in race and gender. Convenience is a poor argument for overriding basic freedoms.”

Long-Standing Problem

Official papers reveal that this discriminatory flaw has been known about for over twelve months. Furthermore, law enforcement lobbied to reverse an initial decision that was intended to mitigate the problem.

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

A Reversed Decision

In reaction, the national police leadership body mandated that the confidence threshold required for possible hits be raised to a point where the disparity was greatly diminished.

However, this decision was reversed the next month after forces complained that the modified technology was generating fewer “useful lines of inquiry”. Internal records indicate the higher threshold reduced the proportion of queries resulting in potential matches from over half to a mere under 15%.

Severe Disparities

Although the authorities refused to say what setting is currently used, the latest NPL study discovered the system could generate incorrect matches 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 specific scenarios the algorithm is more likely to incorrectly include some demographic groups in its search results.”

Operational Effectiveness vs. Bias

Outlining the effect of the temporary raise to the system's confidence threshold, the police records state: “This adjustment significantly reduces the effect of discrimination across legally safeguarded attributes of ethnicity, age and gender but had a substantially detrimental effect on police efficiency”. The papers add that police units complained that “a previously useful tool now delivered results of questionable value”.

Broader Rollout Plans

Meanwhile, the government has launched a ten-week public review on its plans to expand the use of biometric scanning systems. The minister for police Sarah Jones has described the technology as the “biggest breakthrough since DNA matching”.

Expert and Oversight Concerns

The chair of a police oversight board, chair of the independent scrutiny and oversight board for the police race action plan, said: “There was scant consideration 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 policing has undertaken via the equality initiative are failing to be integrated into broader operations. Independent assessments have cautioned that innovative tools are being rolled out in a landscape where ethnic inequalities, inadequate oversight and faulty information gathering continue to exist.

“All deployment of facial recognition must adhere to strict national standards, be independently scrutinised, and demonstrate it reduces rather than compounds racial disparity.”

Official Statement

A Home Office spokesperson said: “The Home Office treat the findings of the study 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 in the coming months and will be subject to further assessment.

“Our priority is protecting the public. This revolutionary tool will support police to apprehend and prosecute offenders. There is officer review in each stage of the process and no further action would be pursued without specialist personnel meticulously examining the results.”