🔗 Share this article

Law enforcement agencies across the United Kingdom successfully lobbied to use a face scanning system known to be biased against females, young people, and individuals from ethnic minority groups, after complaining that a less biased version generated a reduced number of investigative leads.

How the System Works

British police use the national police database to conduct searches using historical face recognition. This procedure involves comparing a reference photograph of a person of interest against a repository of over 19 million mugshots to find possible hits.

Acknowledged Discrimination

The Home Office conceded last week that the technology was flawed. This admission came after a study by the government's National Physical Laboratory determined it misidentified Black and Asian people and women at significantly higher rates than Caucasian males. The ministry 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. Operational ease is a weak argument for overriding fundamental rights.”

Long-Standing Problem

Official papers reveal that this discriminatory flaw has been known about for over twelve months. Furthermore, law enforcement argued to overturn an earlier ruling that was designed to mitigate the problem.

Police bosses were notified of the system's bias in September 2024. The government-ordered laboratory study found the system was more likely to suggest false positives for images depicting females, individuals of Black ethnicity, and those under 40 years old.

A Reversed Decision

In reaction, the national police leadership body ordered that the confidence threshold required for potential matches be raised to a point where the bias 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”. NPCC documents indicate the stricter setting cut the number of queries resulting in potential matches from 56% to a mere 14%.

Severe Disparities

Although the Home Office and NPCC refused to say what threshold is now in operation, the recent NPL study discovered the system could generate false positives for Black women almost 100 times more frequently than for white women at specific configurations.

The Home Office stated on these results: “The testing identified that in a limited set of circumstances the software is has a greater tendency to incorrectly include some population segments in its search results.”

Operational Effectiveness vs. Bias

Describing the effect of the temporary raise to the system's accuracy setting, the NPCC documents note: “The change greatly lessens the impact of bias across legally safeguarded attributes of ethnicity, age and sex but had a significant negative impact on operational effectiveness”. The documents add that forces complained that “a previously useful tool now delivered results of limited benefit”.

Broader Rollout Plans

Meanwhile, the government has opened a two-and-a-half-month public review on its proposals to expand the use of biometric scanning systems. Policing minister Sarah Jones has labeled the tool as the “most significant advance since DNA matching”.

Expert and Oversight Concerns

Abimbola Johnson, chair of the advisory panel for the police race action plan, commented: “There was very little consideration in equality strategy sessions of the facial recognition rollout despite clear relevance with the strategy's goals.

“These revelations demonstrate yet again that the pledges to combat discrimination policing has made via the equality initiative are not being translated into broader operations. Our reports have cautioned that new technologies are being rolled out in a context where ethnic inequalities, inadequate oversight and poor data collection already persist.

“All deployment of this technology must adhere to rigorous official guidelines, be subject to external review, and prove it reduces rather than exacerbates racial disparity.”

Official Statement

A Home Office spokesperson said: “The Home Office treat the conclusions of the study 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 early next year and will be subject to evaluation.

“The foremost aim is ensuring public safety. This gamechanging technology will support police to put criminals and rapists behind bars. There is human involvement in each stage of the procedure and no further action would be pursued without specialist personnel carefully reviewing the results.”