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Police forces across the UK effectively campaigned to use a facial recognition system known to be discriminatory against females, young people, and individuals from minority ethnic backgrounds, following complaints that a less biased version produced fewer investigative leads.

The Technology in Practice

British police utilize the police national database (PND) to carry out retrospective facial recognition searches. This process involves comparing a “probe image” of a person of interest against a database of over 19 million custody photos to find possible hits.

Acknowledged Discrimination

The Home Office conceded last week that the system was flawed. This admission followed a study by the National Physical Laboratory (NPL) determined it incorrectly matched Black and Asian people and females at much greater frequency than white men. The ministry said it “had acted on the findings”.

“It prompts the issue of whether this technology only becomes effective if users tolerate discrimination in race and sex. Operational ease is a weak argument for overriding fundamental rights.”

Known Issue

Internal documents reveal that this bias has been recognized for more than a year. Furthermore, law enforcement argued to overturn an earlier ruling that was intended to mitigate the problem.

Senior officers were informed of the algorithmic discrimination in September 2024. The Home Office-commissioned NPL review concluded the system was had a higher probability to suggest false positives for photos of females, Black people, and those aged 40 and under.

A Policy U-Turn

In reaction, the National Police Chiefs’ Council (NPCC) ordered that the confidence threshold required for potential matches be increased to a point where the disparity was significantly reduced.

However, this decision was reversed the next month following complaints from police that the modified technology was generating a lower number of “investigative leads”. NPCC documents show the stricter setting reduced the proportion of searches that yielded possible identifications from 56% to a mere 14%.

Severe Disparities

Although the authorities declined to specify what threshold is currently used, the latest independent review found the system could generate false positives for women of Black heritage almost 100 times more frequently than for Caucasian women at specific configurations.

The Home Office stated on these results: “Our evaluation identified that in a specific scenarios the software is more likely to incorrectly include some population segments in its search results.”

Operational Effectiveness vs. Bias

Outlining the effect of the brief increase to the system's accuracy setting, the police records note: “This adjustment significantly reduces the impact of discrimination across protected characteristics of ethnicity, age and sex but had a substantially detrimental effect on police efficiency”. The documents further note that forces complained that “a once effective tactic now delivered outcomes of limited benefit”.

Wider Implementation Proposals

Meanwhile, the government has launched a two-and-a-half-month consultation on its proposals to widen the use of biometric scanning systems. The minister for police the relevant minister has labeled the technology as the “most significant advance since DNA matching”.

Criticism from Advisors and Monitors

Abimbola Johnson, chair of the independent scrutiny and oversight board for the national policing equality strategy, said: “We observed scant discussion in race action plan meetings of the facial recognition rollout even with clear relevance with the plan’s concerns.

“This disclosure show once again that the anti-racism commitments policing has undertaken through the equality initiative are not being translated into wider practice. Independent assessments have warned that new technologies are being rolled out in a landscape where racial disparities, inadequate oversight and faulty information gathering already persist.

“Any use of this technology must adhere to rigorous official guidelines, be subject to external review, and prove it diminishes rather than exacerbates ethnic bias.”

Home Office Response

A Home Office spokesperson stated: “We takes the findings of the study seriously and we have implemented changes. A new algorithm has been independently tested and procured, which has no statistically significant bias. It will be trialled early next year and will be subject to evaluation.

“Our priority is ensuring public safety. This gamechanging technology will support police to apprehend and prosecute offenders. There is officer review in each stage of the process and no arrest or charge would be taken without specialist personnel meticulously examining the output.”