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Police forces across the United Kingdom successfully lobbied to deploy a facial recognition system known to be biased against women, young people, and individuals from ethnic minority groups, following complaints that a less biased version produced a reduced number of investigative leads.

The Technology in Practice

UK forces use the police national database (PND) to carry out retrospective facial recognition searches. This process involves comparing a reference photograph of a suspect against a repository of more than 19 million custody photos to find possible hits.

Admitted Bias

The UK interior ministry conceded last week that the system was flawed. This admission came after a review by the National Physical Laboratory (NPL) found it misidentified people of Black and Asian heritage and females at significantly higher rates than white men. The ministry stated it “had acted on the findings”.

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

Long-Standing Problem

Internal documents show that this discriminatory flaw has been recognized for more than a year. Furthermore, law enforcement lobbied to reverse an initial decision that was intended to mitigate the problem.

Senior officers were informed of the system's bias in September 2024. The Home Office-commissioned laboratory study found the system was more likely to produce incorrect matches for photos of women, Black people, and those under 40 years old.

A Reversed Decision

In reaction, the National Police Chiefs’ Council (NPCC) mandated that the confidence threshold required for potential matches be increased to a point where the bias was greatly diminished.

However, this decision was overturned the next month following complaints from police that the adjusted system was producing fewer “useful lines of inquiry”. Internal records show the higher threshold reduced the number of searches resulting in potential matches from 56% to a mere 14%.

Severe Disparities

Although the authorities refused to say what threshold is now in operation, the latest NPL study discovered the system could generate false positives for Black women nearly a hundred times more often than for white women at certain settings.

The ministry commented on these findings: “Our evaluation identified that in a limited set of circumstances the algorithm is has a greater tendency to incorrectly include some population segments in its search results.”

Balancing Utility and Fairness

Describing the effect of the temporary raise to the system's accuracy setting, the NPCC documents state: “This adjustment greatly lessens the impact of discrimination across legally safeguarded attributes of ethnicity, generation and gender but had a substantially detrimental effect on operational effectiveness”. The documents add that police units complained that “a previously useful tool now delivered outcomes of limited benefit”.

Wider Implementation Proposals

Meanwhile, the government has opened a two-and-a-half-month consultation on its proposals to expand the use of biometric scanning systems. The minister for police Sarah Jones has described the tool as the “biggest breakthrough since genetic fingerprinting”.

Expert and Oversight Concerns

Abimbola Johnson, head of the advisory panel for the national policing equality strategy, said: “There was scant consideration through race action plan meetings of the facial recognition rollout even with clear relevance with the strategy's goals.

“This disclosure demonstrate once again that the anti-racism commitments policing has undertaken via the race action plan are not being translated into wider practice. Our reports have warned that innovative tools are being implemented in a landscape where ethnic inequalities, inadequate oversight and poor data collection already persist.

“Any use of this technology must meet strict national standards, be independently scrutinised, and prove it reduces rather than exacerbates ethnic bias.”

Home Office Response

A Home Office spokesperson stated: “We takes the conclusions of the report seriously and we have already taken action. A updated software has been externally evaluated and procured, which has no statistically significant bias. It will be tested in the coming months and will be undergo evaluation.

“The foremost aim is protecting the public. This gamechanging technology will assist police to apprehend and prosecute offenders. There is officer review in every step of the process and no arrest or charge would be taken without trained officers meticulously examining the output.”