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Police forces across the UK successfully lobbied 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 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 “probe image” of a person of interest against a repository of more than 19 million mugshots to find possible hits.

Admitted Bias

The Home Office conceded last week that the technology was biased. This acknowledgment followed a review by the National Physical Laboratory (NPL) found it misidentified Black and Asian people and women at much greater frequency than white men. The Home Office stated it “took steps on the findings”.

“It prompts the question of whether this technology only becomes useful if users accept biases in ethnicity and gender. Operational ease is a poor argument for disregarding fundamental rights.”

Long-Standing Problem

Internal documents reveal that this bias has been recognized for over twelve months. Furthermore, police forces argued to overturn an earlier ruling that was designed to address the problem.

Senior officers were informed of the system's bias in September 2024. The government-ordered NPL review concluded the system was had a higher probability to produce incorrect matches for photos of women, individuals of Black ethnicity, and those under 40 years old.

A Reversed Decision

In response, the national police leadership body mandated that the confidence threshold required for potential matches be raised to a level where the bias was significantly reduced.

However, this decision was reversed the next month following complaints from police that the adjusted system was producing a lower number of “useful lines of inquiry”. NPCC documents indicate the stricter setting reduced the number of queries resulting in possible identifications from over half to a just 14%.

Severe Disparities

Although the authorities declined to specify what setting is currently used, the recent independent review found the system could produce false positives for Black women nearly a hundred times more often than for white women at specific configurations.

The ministry stated on these findings: “Our evaluation found that in a limited set of circumstances the algorithm is more likely to wrongly flag some population segments in its search results.”

Balancing Utility and Fairness

Outlining the impact of the temporary raise to the system's accuracy setting, the police records note: “The change significantly reduces the effect of bias across protected characteristics of race, age and gender but had a significant negative impact on operational effectiveness”. The papers further note that forces complained that “a previously useful tool returned results of limited benefit”.

Broader Rollout Plans

Meanwhile, the UK administration has launched a two-and-a-half-month consultation on its plans to expand the use of biometric scanning systems. Policing minister Sarah Jones has described the tool as the “most significant advance since DNA matching”.

Criticism from Advisors and Monitors

Abimbola Johnson, head of the advisory panel for the national policing equality strategy, said: “There was very little consideration through equality strategy sessions of the facial recognition rollout even with obvious cross-over with the plan’s concerns.

“This disclosure demonstrate yet again that the pledges to combat discrimination the police has undertaken via the equality initiative are not being translated into wider practice. Our reports have warned that innovative tools are being implemented in a context where ethnic inequalities, inadequate oversight and poor data collection already persist.

“Any use of facial recognition must adhere to strict national standards, be independently scrutinised, and prove it reduces rather than exacerbates racial disparity.”

Official Statement

A government representative said: “The Home Office treat the conclusions of the report seriously and we have already taken action. A updated software has been externally evaluated and acquired, which has demonstrated no measurable discrimination. It will be tested early next year and will be subject to further assessment.

“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 further action would be taken without trained officers meticulously examining the output.”