British Law Enforcement Agencies Campaign to Employ Biased Face Scanning Technology

Law enforcement agencies across the UK 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 generated fewer investigative leads.

How the System Works

UK forces utilize the police national database (PND) to carry out retrospective facial recognition searches. This process involves comparing a “probe image” of a suspect against a database of more than 19 million custody photos to identify potential matches.

Admitted Bias

The Home Office admitted last week that the system was flawed. This admission came after a study by the National Physical Laboratory (NPL) found it incorrectly matched Black and Asian people and females at significantly higher rates than Caucasian males. The Home Office said it “took steps on the findings”.

“It prompts the question of whether this technology only becomes useful if users tolerate discrimination in ethnicity and sex. Operational ease is a weak argument for overriding fundamental rights.”

Known Issue

Official papers show that this discriminatory flaw has been known about for more than a year. 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 Home Office-commissioned NPL review found the system was more likely to produce incorrect matches 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 increased to a level where the bias was greatly diminished.

However, this directive was overturned the following month after forces complained that the adjusted system was generating fewer “useful lines of inquiry”. Internal records show the higher threshold cut the number of queries resulting in potential matches from 56% to a mere under 15%.

Profound Inequalities

Although the Home Office and NPCC refused to say what threshold is currently used, the latest NPL study found the system could generate incorrect matches for women of Black heritage nearly a hundred times more often than for white women at certain settings.

The ministry stated on these results: “The testing found that in a specific scenarios the software is more likely to incorrectly include some demographic groups in its search results.”

Operational Effectiveness vs. Bias

Outlining the effect of the brief increase to the system's accuracy setting, the police records state: “The change significantly reduces the impact of bias across legally safeguarded attributes of ethnicity, generation and sex but had a significant negative impact on police efficiency”. The documents further note that police units argued that “a previously useful tool now delivered results of questionable value”.

Wider Implementation Proposals

Meanwhile, the UK administration has opened a two-and-a-half-month consultation on its proposals to widen the use of biometric scanning systems. The minister for police Sarah Jones has described the technology as the “most significant advance since DNA matching”.

Expert and Oversight Concerns

Abimbola Johnson, head of the advisory panel for the national policing equality strategy, said: “There was scant discussion in race action plan meetings of the facial recognition rollout despite obvious cross-over with the plan’s concerns.

“These revelations show yet again that the anti-racism commitments policing has undertaken via 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 poor data collection continue to exist.

“Any use of facial recognition must meet strict national standards, be independently scrutinised, and demonstrate it diminishes rather than exacerbates racial disparity.”

Home Office Response

A Home Office spokesperson stated: “The Home Office treat the findings 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 trialled early next year and will be subject to further assessment.

“Our priority is ensuring public safety. This gamechanging technology will support police to put criminals and rapists behind bars. There is human involvement in every step of the procedure and no arrest or charge would be pursued without trained officers carefully reviewing the results.”