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Police forces across the United Kingdom effectively campaigned to use a face scanning system known to be discriminatory against females, young people, and members of minority ethnic backgrounds, after complaining that a more accurate version produced a reduced number of investigative leads.

The Technology in Practice

UK forces utilize the national police database to carry out retrospective facial recognition searches. This process involves comparing a reference photograph of a person of interest against a repository of more than 19 million mugshots to identify possible hits.

Admitted Bias

The Home Office admitted last week that the system was flawed. This acknowledgment followed a study by the government's National Physical Laboratory determined it misidentified people of Black and Asian heritage and females at much greater frequency than Caucasian males. The ministry stated it “took steps on the findings”.

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

Long-Standing Problem

Official papers show that this discriminatory flaw has been known about for more than a year. Furthermore, law enforcement argued to overturn an earlier ruling that was designed to mitigate the problem.

Senior officers were notified of the algorithmic discrimination in late 2024. The government-ordered NPL review concluded the system was more likely to suggest incorrect matches for images depicting females, Black people, and those under 40 years old.

A Policy U-Turn

In reaction, the National Police Chiefs’ Council (NPCC) ordered that the accuracy setting required for possible hits be raised to a point where the disparity was greatly diminished.

However, this directive was overturned the next month following complaints from police that the modified technology was generating fewer “investigative leads”. Internal records indicate the higher threshold reduced the number of queries that yielded potential matches from 56% to a mere under 15%.

Profound Inequalities

Although the Home Office and NPCC declined to specify what threshold is now in operation, the recent independent review found the system could produce incorrect matches for women of Black heritage almost 100 times more frequently than for white women at specific configurations.

The Home Office commented on these findings: “The testing found that in a limited set of circumstances the software is has a greater tendency to incorrectly include some demographic groups in its match reports.”

Balancing Utility and Fairness

Outlining the effect of the brief increase to the system's accuracy setting, the police records note: “This adjustment significantly reduces the impact of discrimination across legally safeguarded attributes of race, age and gender but had a substantially detrimental effect on operational effectiveness”. The papers further note that forces argued that “a previously useful tool returned results of questionable value”.

Wider Implementation Proposals

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

Expert and Oversight Concerns

Abimbola Johnson, head of the independent scrutiny and oversight board for the police race action plan, commented: “There was very little discussion in equality strategy sessions of the technology deployment despite obvious cross-over with the strategy's goals.

“This disclosure show once again that the pledges to combat discrimination policing has made through the race action plan are not being translated into broader operations. Our reports have cautioned that innovative tools are being rolled out in a context where ethnic inequalities, weak scrutiny and faulty information gathering continue to exist.

“All deployment of this technology must adhere to rigorous official guidelines, be independently scrutinised, and demonstrate it reduces rather than compounds racial disparity.”

Home Office Response

A Home Office spokesperson stated: “We takes the findings of the study seriously and we have implemented changes. 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 undergo evaluation.

“The foremost aim is protecting the public. This revolutionary tool will assist officers to apprehend and prosecute offenders. There is human involvement in every step of the process and no further action would be pursued without specialist personnel carefully reviewing the output.”