🔗 Share this article

Law enforcement agencies across the UK successfully lobbied to deploy a facial recognition system acknowledged as biased against women, 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 conduct searches using historical face recognition. This process involves comparing a reference photograph of a person of interest against a repository of over 19 million custody photos to identify potential matches.

Admitted Bias

The UK interior ministry conceded last week that the technology was flawed. This admission followed a study by the National Physical Laboratory (NPL) determined it misidentified people of Black and Asian heritage and women at much greater frequency than white men. The ministry stated it “had acted on the findings”.

“It prompts the issue of whether facial recognition only becomes useful if users tolerate biases in race and sex. Convenience is a weak argument for disregarding basic freedoms.”

Known Issue

Internal documents reveal that this bias has been known about for more than a year. Furthermore, police forces argued to overturn an earlier ruling that was intended to address the problem.

Police bosses were notified of the algorithmic discrimination in late 2024. The government-ordered laboratory study found the system was more likely to produce incorrect matches for photos of women, individuals of Black ethnicity, and those under 40 years old.

A Reversed Decision

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 greatly diminished.

However, this decision was overturned the following month following complaints from police that the adjusted system was producing fewer “investigative leads”. Internal records indicate the higher threshold reduced the proportion of queries that yielded potential matches from 56% to a just under 15%.

Profound Inequalities

Although the authorities refused to say what threshold is currently used, the latest independent review discovered the system could generate incorrect matches for women of Black heritage almost 100 times more often than for Caucasian women at specific configurations.

The ministry stated on these results: “The testing found that in a specific scenarios the software is has a greater tendency to wrongly flag some demographic groups in its match reports.”

Operational Effectiveness vs. Bias

Outlining the impact of the temporary raise to the system's confidence threshold, the NPCC documents note: “The change significantly reduces the impact of discrimination across legally safeguarded attributes of ethnicity, age and sex but had a substantially detrimental effect on operational effectiveness”. The papers add that forces argued that “a once effective tactic returned results of limited benefit”.

Broader Rollout Plans

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

Expert and Oversight Concerns

Abimbola Johnson, chair of the advisory panel for the police race action plan, said: “We observed scant discussion in equality strategy sessions of the technology deployment despite clear relevance with the plan’s concerns.

“This disclosure show once again that the anti-racism commitments the police has undertaken via the equality initiative are not being translated into wider practice. Independent assessments have warned that innovative tools are being rolled out in a landscape where racial disparities, inadequate oversight and poor data collection already persist.

“All deployment of this technology must adhere to strict national standards, be independently scrutinised, and prove it diminishes rather than compounds ethnic bias.”

Official Statement

A government representative said: “We takes the conclusions of the study with utmost gravity and we have implemented changes. A updated software has been externally evaluated and procured, which has demonstrated no measurable discrimination. It will be trialled in the coming months and will be undergo further assessment.

“Our priority is ensuring public safety. This gamechanging technology will assist officers to put criminals and rapists behind bars. There is human involvement in every step of the procedure and no further action would be taken without specialist personnel carefully reviewing the output.”