🔗 Share this article

Police forces across the UK effectively campaigned to deploy a facial recognition system acknowledged as discriminatory against females, young people, and individuals from minority ethnic backgrounds, after complaining that a less biased version generated a reduced number of potential suspects.

The Technology in Practice

British police utilize the police national database (PND) to conduct retrospective facial recognition searches. This procedure involves comparing a “probe image” of a suspect against a database of more than 19 million mugshots to find potential matches.

Admitted Bias

The UK interior ministry admitted last week that the technology was flawed. This admission followed a study by the National Physical Laboratory (NPL) found it incorrectly matched Black and Asian people and females at significantly higher rates than white men. The ministry stated it “took steps on the findings”.

“This raises the question of whether this technology only becomes effective if users tolerate biases in ethnicity and gender. Convenience is a poor argument for overriding basic freedoms.”

Known Issue

Official papers show that this bias has been known about for over twelve months. Furthermore, law enforcement lobbied to reverse an earlier ruling that was intended to mitigate the problem.

Police bosses were informed of the system's bias in September 2024. The government-ordered laboratory study found the system was more likely to suggest incorrect matches for photos of women, Black people, and those aged 40 and under.

A Reversed Decision

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

However, this directive was overturned the next month following complaints from police that the modified technology was producing a lower number of “investigative leads”. NPCC documents indicate the higher threshold cut the proportion of queries that yielded possible identifications from over half to a just 14%.

Profound Inequalities

Although the authorities declined to specify what setting is currently used, the latest NPL study discovered the system could produce incorrect matches for Black women nearly a hundred times more often than for white women at specific configurations.

The Home Office commented on these results: “Our evaluation found that in a specific scenarios the algorithm is more likely to incorrectly include some population segments in its match reports.”

Balancing Utility and Fairness

Outlining the impact 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 race, age and gender but had a substantially detrimental effect on operational effectiveness”. The papers add that forces argued that “a previously useful tool returned results of questionable value”.

Broader Rollout Plans

Meanwhile, the UK administration has opened a two-and-a-half-month public review on its proposals to expand the use of facial recognition technology. The minister for police Sarah Jones has described the technology as the “biggest breakthrough since DNA matching”.

Criticism from Advisors and Monitors

Abimbola Johnson, chair of the independent scrutiny and oversight board for the police race action plan, said: “We observed very little consideration in race action plan meetings of the facial recognition rollout despite clear relevance with the plan’s concerns.

“This disclosure show once again that the anti-racism commitments policing has undertaken through the equality initiative are not being translated into wider practice. Independent assessments have cautioned that innovative tools are being implemented in a context where ethnic inequalities, weak scrutiny and poor data collection continue to exist.

“Any use of this technology must adhere to strict national standards, be independently scrutinised, and prove it diminishes rather than compounds racial disparity.”

Home Office Response

A Home Office spokesperson said: “The Home Office takes the findings of the study seriously 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 subject to evaluation.

“The foremost aim is ensuring public safety. This revolutionary tool will assist police to apprehend and prosecute offenders. There is human involvement in each stage of the process and no arrest or charge would be pursued without specialist personnel meticulously examining the output.”