🔗 Share this article

Law enforcement agencies across the United Kingdom effectively campaigned to use a face scanning system known to be discriminatory against women, youths, and members of ethnic minority groups, following complaints that a more accurate version generated a reduced number of investigative leads.

The Technology in Practice

British police utilize the police national database (PND) to carry out searches using historical face recognition. This process involves matching a “probe image” of a suspect against a database of more than 19 million custody photos to identify possible hits.

Admitted Bias

The UK interior ministry conceded last week that the technology was flawed. This admission followed a study by the government's National Physical Laboratory determined it misidentified people of Black and Asian heritage and women at much greater frequency than Caucasian males. The ministry stated it “took steps on the findings”.

“It prompts the question of whether facial recognition only becomes effective if users accept discrimination in ethnicity and sex. Operational ease is a poor argument for disregarding basic freedoms.”

Known Issue

Official papers reveal that this bias has been recognized for more than a year. Furthermore, police forces lobbied to reverse an earlier ruling that was designed to mitigate the problem.

Police bosses were informed of the algorithmic discrimination in September 2024. The Home Office-commissioned laboratory study found the system was more likely to suggest false positives for photos of females, individuals of Black ethnicity, and those under 40 years old.

A Reversed Decision

In reaction, the National Police Chiefs’ Council (NPCC) ordered that the confidence threshold required for possible hits be increased to a level where the bias was significantly reduced.

However, this decision was overturned the following month following complaints from police that the modified technology was producing a lower number of “investigative leads”. NPCC documents show the higher threshold reduced the proportion of queries resulting in possible identifications from over half to a just 14%.

Profound Inequalities

Although the authorities declined to specify what setting is now in operation, the latest NPL study discovered the system could generate false positives for women of Black heritage almost 100 times more frequently than for white women at specific configurations.

The ministry commented on these findings: “The testing identified that in a specific scenarios the software is has a greater tendency to incorrectly include some population segments in its search results.”

Balancing Utility and Fairness

Describing the impact of the temporary raise to the system's confidence threshold, the police records state: “The change greatly lessens the effect of bias across legally safeguarded attributes of race, generation and sex but had a substantially detrimental effect on operational effectiveness”. The documents add that forces argued that “a previously useful tool returned outcomes of questionable value”.

Wider Implementation Proposals

Meanwhile, the UK administration has launched a ten-week public review on its plans to expand the use of biometric scanning systems. The minister for police Sarah Jones has described the technology as the “most significant advance since genetic fingerprinting”.

Expert and Oversight Concerns

The chair of a police oversight board, chair of the advisory panel for the police race action plan, commented: “There was very little consideration through race action plan meetings of the facial recognition rollout despite clear relevance with the strategy's goals.

“This disclosure show once again that the pledges to combat discrimination the police has made through the race action plan are not being translated into wider practice. Independent assessments have cautioned that new technologies are being implemented in a context where racial disparities, weak scrutiny and faulty information gathering continue to exist.

“Any use of this technology must meet rigorous official guidelines, be subject to external review, and prove it reduces rather than compounds ethnic bias.”

Home Office Response

A Home Office spokesperson stated: “We takes the findings of the report seriously and we have already taken action. A updated software has been externally evaluated and acquired, which has no statistically significant bias. 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 apprehend and prosecute offenders. There is officer review in every step of the process and no arrest or charge would be taken without specialist personnel carefully reviewing the results.”