🔗 Share this article

Law enforcement agencies across the UK effectively campaigned to deploy a face scanning system acknowledged as discriminatory against females, youths, and members of minority ethnic backgrounds, after complaining that a less biased version generated a reduced number of potential suspects.

How the System Works

British police use the police national database (PND) to carry out searches using historical face recognition. This procedure involves matching a “probe image” of a person of interest against a repository of more than 19 million mugshots to identify potential matches.

Acknowledged Discrimination

The Home Office admitted last week that the technology was flawed. This admission followed a study by the government's National Physical Laboratory found it incorrectly matched Black and Asian people and women at significantly higher rates than white men. The Home Office stated it “had acted on the findings”.

“This raises the issue of whether this technology only becomes useful if users accept biases in ethnicity and gender. Convenience is a weak argument for disregarding basic freedoms.”

Long-Standing Problem

Official papers show that this bias has been recognized for over twelve months. Furthermore, law enforcement argued to overturn an initial decision that was designed to mitigate the problem.

Police bosses were informed of the system's bias in September 2024. The Home Office-commissioned NPL review concluded the system was more likely to suggest false positives for photos of women, Black people, and those under 40 years old.

A Policy U-Turn

In response, the national police leadership body mandated that the confidence threshold required for possible hits be raised to a point where the bias was greatly diminished.

However, this decision was overturned the next month after forces complained that the adjusted system was generating a lower number of “investigative leads”. NPCC documents indicate the higher threshold reduced the proportion of queries that yielded potential matches from over half to a just 14%.

Severe Disparities

Although the Home Office and NPCC declined to specify what setting is now in operation, the recent independent review found the system could produce incorrect matches for women of Black heritage almost 100 times more often than for Caucasian women at certain settings.

The ministry commented on these results: “Our evaluation identified that in a limited set of circumstances the algorithm is has a greater tendency to incorrectly include some population segments in its match reports.”

Balancing Utility and Fairness

Outlining the impact of the brief increase to the system's accuracy setting, the NPCC documents state: “The change significantly reduces the effect of bias across protected characteristics of race, age and sex but had a significant negative impact on operational effectiveness”. The papers 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 biometric scanning systems. Policing minister the relevant minister has labeled the tool as the “biggest breakthrough since genetic fingerprinting”.

Expert and Oversight Concerns

The chair of a police oversight board, head of the independent scrutiny and oversight board for the police race action plan, commented: “We observed very little discussion in equality strategy sessions of the facial recognition rollout despite obvious cross-over with the strategy's goals.

“These revelations show yet again that the anti-racism commitments policing has made via the equality initiative are failing to be integrated into broader operations. Independent assessments have warned that new technologies are being rolled out in a context where racial disparities, inadequate oversight and faulty information gathering already persist.

“All deployment of this technology must meet rigorous official guidelines, be independently scrutinised, and demonstrate it diminishes rather than compounds ethnic bias.”

Official Statement

A Home Office spokesperson stated: “We treat the conclusions of the study seriously and we have already taken action. A updated software has been externally evaluated and procured, which has no statistically significant bias. It will be tested in the coming months and will be subject to evaluation.

“Our priority is ensuring public safety. This revolutionary tool will assist officers to put criminals and rapists behind bars. There is human involvement in each stage of the process and no further action would be pursued without specialist personnel carefully reviewing the output.”