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Law enforcement agencies across the UK successfully lobbied to deploy a face scanning system known to be discriminatory against females, young people, and members of minority ethnic backgrounds, following complaints that a more accurate version produced fewer potential suspects.

The Technology in Practice

UK forces use the police national database (PND) to carry out searches using historical face recognition. This process involves comparing a “probe image” of a suspect against a repository of more than 19 million mugshots to identify possible hits.

Acknowledged Discrimination

The UK interior ministry admitted last week that the technology was flawed. This acknowledgment came after a study by the National Physical Laboratory (NPL) found it misidentified people of Black and Asian heritage and females at much greater frequency than Caucasian males. The Home Office said it “took steps on the findings”.

“This raises the issue of whether facial recognition only becomes useful if users accept discrimination in ethnicity and gender. Convenience is a poor argument for disregarding fundamental rights.”

Known Issue

Official papers show that this discriminatory flaw has been recognized for more than a year. Furthermore, police forces lobbied to reverse an initial decision that was designed to address the problem.

Senior officers were notified of the system's bias in September 2024. The government-ordered NPL review concluded the system was had a higher probability to suggest incorrect matches for images depicting women, individuals of Black ethnicity, and those aged 40 and under.

A Policy U-Turn

In reaction, the National Police Chiefs’ Council (NPCC) mandated that the confidence threshold required for possible hits be increased to a level where the bias was significantly reduced.

However, this directive was reversed the following month following complaints from police that the modified technology was producing a lower number of “useful lines of inquiry”. Internal records indicate the stricter setting reduced the proportion of searches that yielded potential matches from 56% to a just 14%.

Severe Disparities

Although the Home Office and NPCC refused to say what threshold is currently used, the recent NPL study discovered the system could generate incorrect matches for women of Black heritage almost 100 times more often than for Caucasian women at certain settings.

The Home Office commented on these findings: “Our evaluation found that in a specific scenarios the software is more likely to wrongly flag some population segments in its search results.”

Operational Effectiveness vs. Bias

Describing the effect of the brief increase to the system's confidence threshold, the NPCC documents state: “This adjustment greatly lessens the impact of discrimination across protected characteristics of ethnicity, generation and sex but had a substantially detrimental effect on operational effectiveness”. The papers add that forces complained that “a once effective tactic now delivered results of questionable value”.

Broader Rollout Plans

Meanwhile, the government has launched a two-and-a-half-month consultation on its plans to expand the use of biometric scanning systems. Policing minister the relevant minister has labeled the tool as the “most significant advance since genetic fingerprinting”.

Expert and Oversight Concerns

Abimbola Johnson, head of the independent scrutiny and oversight board for the police race action plan, said: “We observed scant discussion in race action plan meetings of the technology deployment even with clear relevance with the strategy's goals.

“These revelations demonstrate yet again that the anti-racism commitments the police has undertaken via the race action plan are failing to be integrated into broader operations. Our reports have warned that new technologies are being rolled out in a context where ethnic inequalities, inadequate oversight and faulty information gathering continue to exist.

“Any use of facial recognition must meet rigorous official guidelines, be subject to external review, and demonstrate it reduces rather than exacerbates racial disparity.”

Home Office Response

A government representative stated: “We takes the conclusions of the report with utmost gravity and we have already taken action. A updated software has been independently tested and procured, which has no statistically significant bias. It will be tested in the coming months and will be undergo evaluation.

“Our priority is ensuring public safety. This gamechanging technology will support police to apprehend and prosecute offenders. There is human involvement in every step of the procedure and no further action would be taken without specialist personnel carefully reviewing the output.”