British Police Forces Lobbied to Use Biased Facial Recognition Technology

Law enforcement agencies across the United Kingdom successfully lobbied to use a facial recognition system acknowledged as biased against women, youths, and individuals from ethnic minority groups, following complaints that a less biased version produced a reduced number of investigative leads.

The Technology in Practice

British police utilize the national police database to carry out searches using historical face recognition. This procedure involves matching a “probe image” of a suspect against a database of over 19 million custody photos to find potential matches.

Acknowledged Discrimination

The Home Office conceded last week that the system was flawed. This acknowledgment came after a review by the National Physical Laboratory (NPL) determined it misidentified people of Black and Asian heritage and females at significantly higher rates than white men. The ministry stated it “had acted on the findings”.

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

Long-Standing Problem

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

Senior officers were informed of the system's bias in late 2024. The Home Office-commissioned NPL review found the system was had a higher probability to suggest incorrect matches for photos of women, individuals of Black ethnicity, and those under 40 years old.

A Reversed Decision

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

However, this decision was reversed the following month after forces complained that the adjusted system was producing fewer “investigative leads”. Internal records indicate the higher threshold reduced the proportion of searches resulting in potential matches from 56% to a mere 14%.

Profound Inequalities

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

The Home Office commented on these findings: “Our evaluation identified that in a limited set of circumstances the software is has a greater tendency to wrongly flag some demographic groups in its match reports.”

Balancing Utility and Fairness

Outlining the effect of the brief increase to the system's accuracy setting, the police records note: “The change greatly lessens the effect of discrimination across protected characteristics of ethnicity, age and sex but had a substantially detrimental effect on operational effectiveness”. The papers further note that police units complained that “a previously useful tool returned results of limited benefit”.

Broader Rollout Plans

Meanwhile, the UK administration has launched a two-and-a-half-month public review on its plans to expand the use of biometric scanning systems. Policing minister the relevant minister has described the technology 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 national policing equality strategy, commented: “We observed very little consideration in race action plan meetings of the technology deployment despite obvious cross-over with the strategy's goals.

“This disclosure demonstrate once again that the pledges to combat discrimination the police has made through the race action plan are failing to be integrated into wider practice. Independent assessments have warned that innovative tools are being implemented in a context 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 reduces rather than compounds racial disparity.”

Official Statement

A Home Office spokesperson stated: “The Home Office takes the findings 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 trialled early next year and will be subject to further assessment.

“Our priority is protecting the public. This gamechanging technology will assist officers to put criminals and rapists behind bars. There is human involvement in every step of the procedure and no arrest or charge would be taken without trained officers carefully reviewing the output.”