🔗 Share this article

Law enforcement agencies across the United Kingdom effectively campaigned to use a facial recognition system acknowledged as biased against females, youths, and individuals from ethnic minority groups, following complaints that a less biased version produced fewer investigative leads.

How the System Works

UK forces use the police national database (PND) to conduct searches using historical face recognition. This procedure entails matching a “probe image” of a suspect against a database of more than 19 million mugshots to identify potential matches.

Acknowledged Discrimination

The UK interior ministry conceded last week that the technology was biased. This acknowledgment followed a study by the National Physical Laboratory (NPL) determined it misidentified people of Black and Asian heritage and women at significantly higher rates than Caucasian males. The ministry stated it “took steps on the findings”.

“This raises the issue of whether facial recognition only becomes effective if users accept discrimination in race and gender. Operational ease is a weak argument for disregarding basic freedoms.”

Known Issue

Official papers show that this bias has been recognized for over twelve months. Furthermore, police forces lobbied to reverse 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 photos of females, individuals of Black ethnicity, and those under 40 years old.

A Reversed Decision

In reaction, the national police leadership body mandated that the accuracy setting required for possible hits be raised to a level where the disparity was significantly reduced.

However, this decision was reversed the next month following complaints from police that the adjusted system was producing a lower number of “investigative leads”. Internal records show the higher threshold cut the proportion of queries resulting in potential matches from 56% to a mere 14%.

Severe Disparities

Although the authorities declined to specify what threshold is now in operation, the latest NPL study found the system could generate incorrect matches for Black women almost 100 times more frequently than for Caucasian women at specific configurations.

The Home Office stated on these findings: “Our evaluation found that in a limited set of circumstances the algorithm is has a greater tendency to wrongly flag some demographic groups in its search results.”

Balancing Utility and Fairness

Describing the effect of the temporary raise to the system's accuracy setting, the police records state: “The change significantly reduces the effect of bias across legally safeguarded attributes of race, generation and gender but had a significant negative impact on operational effectiveness”. The papers further note that forces argued that “a previously useful tool returned outcomes of limited benefit”.

Broader Rollout Plans

Meanwhile, the UK administration has opened a ten-week consultation on its plans to widen the use of biometric scanning systems. Policing minister Sarah Jones has labeled the technology as the “most significant advance since genetic fingerprinting”.

Criticism from Advisors and Monitors

The chair of a police oversight board, chair of the independent scrutiny and oversight board for the national policing equality strategy, said: “There was very little discussion in equality strategy sessions of the facial recognition rollout despite obvious cross-over with the strategy's goals.

“This disclosure demonstrate once again that the anti-racism commitments the police has undertaken via the equality initiative are failing to be integrated into broader operations. Independent assessments have cautioned that innovative tools are being implemented in a landscape where ethnic inequalities, weak scrutiny and poor data collection continue to exist.

“All deployment of facial recognition must meet rigorous official guidelines, be subject to external review, and prove it diminishes rather than exacerbates ethnic bias.”

Official Statement

A Home Office spokesperson stated: “We treat the conclusions of the study with utmost gravity and we have implemented changes. A new algorithm has been externally evaluated and acquired, which has demonstrated no measurable discrimination. It will be trialled in the coming months and will be undergo evaluation.

“The foremost aim is protecting the public. This gamechanging technology will support officers to put criminals and rapists behind bars. There is human involvement in every step of the process and no arrest or charge would be pursued without specialist personnel meticulously examining the results.”