British Law Enforcement Agencies Lobbied to Use Biased Face Scanning Technology

Police forces across the UK effectively campaigned to deploy a face scanning system acknowledged as biased against women, youths, and members of ethnic minority groups, following complaints that a less biased version generated a reduced number of potential suspects.

The Technology in Practice

UK forces use the police national database (PND) to carry out searches using historical face recognition. This procedure involves comparing a reference photograph of a suspect against a repository of more than 19 million custody photos to identify possible hits.

Admitted Bias

The Home Office conceded last week that the system was flawed. This admission followed a review by the National Physical Laboratory (NPL) found it incorrectly matched people of Black and Asian heritage and females at much greater frequency than white men. The ministry said it “had acted on the findings”.

“It prompts the issue of whether facial recognition only becomes useful if users tolerate discrimination in ethnicity and gender. Convenience is a weak argument for disregarding basic freedoms.”

Long-Standing Problem

Internal documents reveal that this discriminatory flaw has been known about for more than a year. Furthermore, police forces argued to overturn an earlier ruling that was intended to mitigate the problem.

Police bosses were informed of the system's bias in late 2024. The government-ordered laboratory study concluded the system was more likely to suggest incorrect matches for images depicting women, Black people, and those under 40 years old.

A Policy U-Turn

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

However, this decision was reversed the following month following complaints from police that the adjusted system was generating a lower number of “investigative leads”. Internal records show the higher threshold cut the proportion of searches resulting in potential matches from over half to a just 14%.

Severe Disparities

Although the Home Office and NPCC refused to say what threshold is now in operation, the latest NPL study found the system could generate incorrect matches for Black women nearly a hundred times more frequently than for Caucasian women at certain settings.

The Home Office commented on these findings: “The testing found that in a specific scenarios the software is has a greater tendency to incorrectly include some demographic groups in its search results.”

Operational Effectiveness vs. Bias

Outlining the impact of the brief increase to the system's confidence threshold, the NPCC documents state: “The change greatly lessens the effect of bias across legally safeguarded attributes of ethnicity, generation and gender but had a significant negative impact on operational effectiveness”. The documents add that police units argued that “a once effective tactic now delivered results of limited benefit”.

Broader Rollout Plans

Meanwhile, the UK administration has opened a two-and-a-half-month consultation on its proposals to widen the use of facial recognition technology. The minister for police the relevant minister has labeled the technology as the “biggest breakthrough 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, said: “There was scant discussion in equality strategy sessions of the facial recognition rollout despite obvious cross-over with the plan’s concerns.

“This disclosure demonstrate once again that the anti-racism commitments policing has undertaken through the race action plan are failing to be integrated into wider practice. Independent assessments have cautioned that innovative tools are being implemented in a context where racial disparities, inadequate oversight and poor data collection continue to exist.

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

Home Office Response

A Home Office spokesperson stated: “We takes the findings of the report seriously and we have implemented changes. A new algorithm has been externally evaluated and acquired, which has no statistically significant bias. It will be trialled early next year and will be subject to evaluation.

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