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Law enforcement agencies across the UK successfully lobbied to use a face scanning system acknowledged as biased against women, youths, and individuals from ethnic minority groups, following complaints that a more accurate version generated 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 matching a reference photograph of a suspect against a repository of over 19 million custody photos to find possible hits.

Admitted Bias

The Home Office conceded last week that the system was flawed. This admission followed a review by the government's National Physical Laboratory found it incorrectly matched Black and Asian people and women at significantly higher rates than Caucasian males. The ministry said it “had acted on the findings”.

“This raises the issue of whether facial recognition only becomes effective 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 bias has been known about for over twelve months. Furthermore, police forces argued to overturn an earlier ruling that was intended to mitigate the problem.

Senior officers were informed of the algorithmic discrimination in late 2024. The government-ordered laboratory study concluded the system was had a higher probability to produce incorrect matches for images depicting women, Black people, and those aged 40 and under.

A Policy U-Turn

In response, the national police leadership body mandated that the confidence threshold required for possible hits be increased to a level where the disparity was significantly reduced.

However, this decision was reversed the following month following complaints from police that the modified technology was generating fewer “useful lines of inquiry”. NPCC documents indicate the higher threshold reduced the number of searches that yielded potential matches from 56% to a mere 14%.

Severe Disparities

Although the authorities refused to say what setting is now in operation, the recent NPL study found the system could produce incorrect matches for Black women nearly a hundred times more often than for white women at specific configurations.

The ministry commented on these findings: “Our evaluation identified that in a limited set of circumstances the software is has a greater tendency to incorrectly include some demographic groups in its match reports.”

Operational Effectiveness vs. Bias

Outlining the impact of the brief increase to the system's accuracy setting, the NPCC documents note: “The change significantly reduces the effect of bias across protected characteristics of ethnicity, generation and gender but had a significant negative impact on operational effectiveness”. The papers add that forces complained that “a once effective tactic now delivered outcomes of questionable value”.

Wider Implementation Proposals

Meanwhile, the government has launched a two-and-a-half-month public review on its plans to expand the use of biometric scanning systems. The minister for police the relevant minister has described the tool as the “most significant advance since genetic fingerprinting”.

Expert and Oversight Concerns

The chair of a police oversight board, head of the advisory panel for the national policing equality strategy, commented: “We observed very little discussion through race action plan meetings of the facial recognition rollout even with obvious cross-over with the strategy's goals.

“This disclosure demonstrate once again that the pledges to combat discrimination the police has undertaken via the equality initiative are not being translated into broader operations. Independent assessments have cautioned that new technologies are being rolled out in a landscape where racial disparities, inadequate oversight and faulty information gathering already persist.

“All deployment of this technology must meet rigorous official guidelines, be independently scrutinised, and prove it diminishes rather than compounds ethnic bias.”

Official Statement

A Home Office spokesperson said: “We takes the conclusions of the study seriously and we have implemented changes. A updated software has been externally evaluated and acquired, which has no statistically significant bias. It will be trialled early next year and will be undergo further assessment.

“Our priority is ensuring public safety. This gamechanging technology will assist police to put criminals and rapists behind bars. There is human involvement in each stage of the process and no further action would be pursued without specialist personnel carefully reviewing the output.”