🔗 Share this article

Law enforcement agencies across the United Kingdom successfully lobbied to use a face scanning system acknowledged as discriminatory against women, youths, and individuals from ethnic minority groups, following complaints that a more accurate version generated a reduced number of potential suspects.

The Technology in Practice

UK forces use the national police database to conduct retrospective facial recognition searches. This process entails matching a reference photograph of a suspect against a database of over 19 million custody photos to find possible hits.

Admitted Bias

The Home Office conceded last week that the system was biased. This acknowledgment followed a study by the government's National Physical Laboratory found it incorrectly matched people of Black and Asian heritage and women at significantly higher rates than white men. The Home Office said it “took steps on the findings”.

“It prompts the issue of whether this technology only becomes useful if users accept discrimination in ethnicity and sex. Convenience is a weak argument for disregarding basic freedoms.”

Long-Standing Problem

Official papers reveal that this bias has been known about for over twelve months. Furthermore, law enforcement argued to overturn an earlier ruling that was designed to mitigate the problem.

Senior officers were informed of the system's bias in September 2024. The Home Office-commissioned laboratory study concluded the system was more likely to produce false positives for images depicting women, Black people, and those aged 40 and under.

A Reversed Decision

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

However, this directive was reversed the next month following complaints from police that the adjusted system was producing fewer “useful lines of inquiry”. Internal records indicate the stricter setting cut the proportion of searches resulting in possible identifications from 56% to a just 14%.

Profound Inequalities

Although the Home Office and NPCC declined to specify what threshold is currently used, the recent independent review discovered the system could generate false positives for Black women nearly a hundred times more frequently than for white women at certain settings.

The Home Office stated on these results: “The testing found that in a limited set of circumstances the software is more likely to incorrectly include some demographic groups in its search results.”

Operational Effectiveness vs. Bias

Describing the impact of the brief increase to the system's confidence threshold, the police records state: “This adjustment significantly reduces the impact of bias across protected characteristics of race, age and sex but had a substantially detrimental effect on police efficiency”. The documents further note that police units complained that “a previously useful tool returned results of limited benefit”.

Wider Implementation Proposals

Meanwhile, the UK administration has opened a ten-week public review on its plans to widen the use of biometric scanning systems. Policing minister the relevant minister has labeled the technology as the “most significant advance since DNA matching”.

Expert and Oversight Concerns

The chair of a police oversight board, head of the advisory panel for the police race action plan, commented: “We observed scant discussion through race action plan meetings of the technology deployment despite clear relevance with the plan’s concerns.

“These revelations demonstrate once again that the pledges to combat discrimination policing has undertaken through the equality initiative are failing to be integrated into wider practice. Independent assessments have cautioned that new technologies are being implemented in a landscape where racial disparities, weak scrutiny and faulty information gathering already persist.

“All deployment of this technology must adhere to strict national standards, be subject to external review, and demonstrate it diminishes rather than compounds ethnic bias.”

Home Office Response

A Home Office spokesperson said: “We takes the findings of the study with utmost gravity and we have already taken action. A new algorithm 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 gamechanging technology will assist officers to put criminals and rapists behind bars. There is human involvement in each stage of the procedure and no arrest or charge would be taken without specialist personnel meticulously examining the output.”