British Police Forces Campaign to Employ Biased Facial Recognition Systems

Police forces across the United Kingdom successfully lobbied to deploy a facial recognition system known to be discriminatory against females, youths, and individuals from ethnic minority groups, after complaining that a less biased version generated fewer investigative leads.

The Technology in Practice

UK forces utilize the police national database (PND) to carry out retrospective facial recognition searches. This process involves matching a “probe image” of a person of interest against a repository of more than 19 million mugshots to find potential matches.

Acknowledged Discrimination

The Home Office conceded last week that the technology was flawed. This admission followed a review by the government's National Physical Laboratory determined 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”.

“This raises the question of whether facial recognition only becomes effective if users tolerate discrimination in ethnicity and gender. Operational ease is a poor argument for disregarding basic freedoms.”

Known Issue

Internal documents reveal that this bias has been recognized for over twelve months. 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 NPL review concluded the system was more likely to produce false positives for images depicting females, individuals of Black ethnicity, and those under 40 years old.

A Policy U-Turn

In response, the national police leadership body ordered that the accuracy setting required for possible hits be increased to a point where the bias was greatly diminished.

However, this decision was reversed the next month after forces complained that the modified technology was generating a lower number of “investigative leads”. NPCC documents indicate the higher threshold reduced the proportion of queries resulting in potential matches from over half to a mere under 15%.

Severe Disparities

Although the Home Office and NPCC refused to say what setting is currently used, the recent NPL study discovered the system could generate incorrect matches for Black women almost 100 times more often than for white women at certain settings.

The Home Office commented on these results: “Our evaluation found that in a limited set of circumstances the algorithm is more likely to wrongly flag some demographic groups in its match reports.”

Operational Effectiveness vs. Bias

Outlining the effect of the temporary raise to the system's confidence threshold, the NPCC documents note: “This adjustment greatly lessens the effect of bias across protected characteristics of ethnicity, generation and sex but had a significant negative impact on police efficiency”. The documents add that forces argued that “a once effective tactic now delivered outcomes of limited benefit”.

Broader Rollout Plans

Meanwhile, the government has launched a two-and-a-half-month consultation on its proposals to widen the use of biometric scanning systems. Policing minister the relevant minister has described the tool as the “biggest breakthrough since genetic fingerprinting”.

Criticism from Advisors and Monitors

The chair of a police oversight board, head of the independent scrutiny and oversight board for the police race action plan, said: “There was very little consideration through race action plan meetings of the facial recognition rollout even with clear relevance with the plan’s concerns.

“These revelations show once again that the anti-racism commitments the police has made through the race action plan are failing to be integrated into wider practice. Our reports have warned that new technologies are being rolled out in a landscape where racial disparities, weak scrutiny and faulty information gathering continue to exist.

“Any use of facial recognition must meet rigorous official guidelines, be subject to external review, and demonstrate it diminishes rather than compounds ethnic bias.”

Home Office Response

A government representative said: “The Home Office takes the findings of the report with utmost gravity and we have implemented changes. A updated software has been externally evaluated and acquired, which has no statistically significant bias. It will be tested in the coming months and will be undergo evaluation.

“Our priority is protecting the public. This revolutionary tool will support officers to apprehend and prosecute offenders. There is officer review in every step of the process and no arrest or charge would be pursued without trained officers carefully reviewing the results.”