🔗 Share this article

Police forces across the UK effectively campaigned to deploy a facial recognition system acknowledged as discriminatory against women, young people, and members of minority ethnic backgrounds, following complaints that a less biased version generated fewer potential suspects.

How the System Works

British police use the national police database to carry out searches using historical face recognition. This process entails comparing a reference photograph of a suspect against a repository of more than 19 million mugshots to find possible hits.

Acknowledged Discrimination

The Home Office conceded last week that the system was flawed. This acknowledgment followed a study by the National Physical Laboratory (NPL) found it incorrectly matched Black and Asian people and women at significantly higher rates than Caucasian males. The ministry stated it “took steps on the findings”.

“This raises the question of whether this technology only becomes effective if users accept biases in ethnicity and gender. Operational ease is a weak argument for disregarding fundamental rights.”

Known Issue

Internal documents reveal that this bias has been known about for more than a year. Furthermore, police forces lobbied to reverse an initial decision that was intended to address the problem.

Police bosses were informed of the algorithmic discrimination in September 2024. The Home Office-commissioned laboratory study concluded the system was had a higher probability to produce false positives for images depicting women, Black people, and those aged 40 and under.

A Policy U-Turn

In reaction, the national police leadership body mandated that the accuracy setting required for possible hits be raised to a point where the bias was greatly diminished.

However, this directive was reversed the following month following complaints from police that the modified technology was generating fewer “investigative leads”. NPCC documents show the stricter setting reduced the proportion of searches resulting in possible identifications from over half to a just 14%.

Severe Disparities

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

The Home Office commented on these findings: “Our evaluation found that in a limited set of circumstances the software is has a greater tendency to wrongly flag some population segments in its search results.”

Operational Effectiveness vs. Bias

Describing the effect of the brief increase to the system's confidence threshold, the NPCC documents state: “This adjustment significantly reduces the impact of bias across legally safeguarded attributes of race, generation and sex but had a significant negative impact on police efficiency”. The documents further note that police units complained that “a previously useful tool returned results of questionable value”.

Broader Rollout Plans

Meanwhile, the UK administration has launched a two-and-a-half-month public review on its plans to widen the use of facial recognition technology. Policing minister the relevant minister has described the technology as the “most significant advance since genetic fingerprinting”.

Expert and Oversight Concerns

Abimbola Johnson, chair of the advisory panel for the police race action plan, commented: “There was scant consideration in race action plan meetings of the technology deployment even with obvious cross-over with the strategy's goals.

“This disclosure show yet again that the anti-racism commitments the police has made through the race action plan are not being translated into wider practice. Our reports have warned that new technologies are being rolled out in a landscape where ethnic inequalities, inadequate oversight and faulty information gathering already persist.

“Any use of this technology must meet strict national standards, be subject to external review, and demonstrate it diminishes rather than exacerbates ethnic bias.”

Home Office Response

A Home Office spokesperson said: “We takes the conclusions of the study with utmost gravity and we have already taken action. A new algorithm has been independently tested and acquired, which has demonstrated no measurable discrimination. It will be tested early next year and will be subject to further assessment.

“Our priority is protecting the public. This gamechanging technology will support police to apprehend and prosecute offenders. There is officer review in every step of the process and no further action would be pursued without specialist personnel meticulously examining the output.”