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Police forces across the UK effectively campaigned to deploy a facial recognition system acknowledged as discriminatory against females, young people, and members of ethnic minority groups, after complaining that a more accurate version produced fewer potential suspects.

The Technology in Practice

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

Admitted Bias

The UK interior ministry admitted last week that the technology was flawed. This acknowledgment came after a review by the National Physical Laboratory (NPL) found it misidentified Black and Asian people and women at significantly higher rates than Caucasian males. The ministry said it “took steps on the findings”.

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

Long-Standing Problem

Official papers reveal that this discriminatory flaw has been recognized for over twelve months. Furthermore, police forces lobbied to reverse an earlier ruling that was designed to address the problem.

Police bosses were informed of the algorithmic discrimination in late 2024. The government-ordered NPL review concluded the system was more likely to suggest incorrect matches for photos of women, individuals of Black ethnicity, and those aged 40 and under.

A Policy U-Turn

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

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

Severe Disparities

Although the Home Office and NPCC declined to specify what threshold is currently used, the recent independent review discovered the system could produce false positives for women of Black heritage almost 100 times more often than for Caucasian women at specific configurations.

The ministry stated on these results: “Our evaluation identified that in a specific scenarios the algorithm is has a greater tendency to incorrectly include some demographic groups in its match reports.”

Operational Effectiveness vs. Bias

Outlining the effect of the temporary raise to the system's confidence threshold, the police records state: “This adjustment greatly lessens the effect of bias across legally safeguarded attributes of ethnicity, age and gender but had a substantially detrimental effect on operational effectiveness”. The documents add that police units complained that “a once effective tactic now delivered results of limited benefit”.

Wider Implementation Proposals

Meanwhile, the UK administration has launched a ten-week consultation on its proposals to expand the use of biometric scanning systems. The minister for police the relevant minister has labeled the tool as the “most significant advance since genetic fingerprinting”.

Expert and Oversight Concerns

Abimbola Johnson, head of the advisory panel for the national policing equality strategy, commented: “There was very little consideration through equality strategy sessions of the technology deployment despite obvious cross-over with the plan’s concerns.

“These revelations show once again that the pledges to combat discrimination the police has undertaken via the race action plan are failing to be integrated into broader operations. Our reports have warned that innovative tools are being rolled out in a context where racial disparities, inadequate oversight and poor data collection already persist.

“Any use of this technology must adhere to rigorous official guidelines, be independently scrutinised, and demonstrate it reduces rather than compounds racial disparity.”

Home Office Response

A government representative said: “The Home Office treat the conclusions of the study with utmost gravity and we have already taken action. A new algorithm has been independently tested and procured, which has no statistically significant bias. It will be trialled in the coming months 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 officer review in each stage of the process and no further action would be taken without specialist personnel carefully reviewing the output.”