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Law enforcement agencies across the UK successfully lobbied to use a face scanning system acknowledged as biased against females, youths, and individuals from ethnic minority groups, after complaining that a more accurate version generated a reduced number of investigative leads.

How the System Works

UK forces utilize the national police database to carry out retrospective facial recognition searches. This process entails comparing a “probe image” of a suspect against a repository of over 19 million mugshots to identify potential matches.

Admitted Bias

The Home Office admitted last week that the technology was biased. This admission followed a study by the National Physical Laboratory (NPL) found it misidentified people of Black and Asian heritage and females at significantly higher rates than Caucasian males. The ministry stated it “had acted on the findings”.

“It prompts the issue of whether this technology only becomes effective if users tolerate discrimination in ethnicity and gender. Convenience is a poor argument for overriding basic freedoms.”

Known Issue

Internal documents reveal that this bias has been recognized for more than a year. Furthermore, law enforcement lobbied to reverse an initial decision that was designed to address the problem.

Police bosses were informed of the algorithmic discrimination in late 2024. The Home Office-commissioned laboratory study concluded the system was had a higher probability to produce incorrect matches for images depicting females, individuals of Black ethnicity, and those under 40 years old.

A Reversed Decision

In response, the national police leadership body mandated that the accuracy setting required for potential matches be increased to a point where the disparity was greatly diminished.

However, this decision was reversed the following month following complaints from police that the adjusted system was generating fewer “investigative leads”. Internal records show the higher threshold reduced the proportion of searches that yielded possible identifications from over half to a just 14%.

Profound Inequalities

Although the authorities refused to say what setting is currently used, the latest independent review discovered the system could produce false positives for women of Black heritage nearly a hundred times more frequently than for white women at specific configurations.

The Home Office stated on these results: “Our evaluation identified that in a specific scenarios the software is more likely to incorrectly include some population segments in its search results.”

Balancing Utility and Fairness

Describing the effect of the brief increase to the system's confidence threshold, the police records state: “The change significantly reduces the effect of bias across legally safeguarded attributes 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 returned 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. The minister for police Sarah Jones has labeled the tool as the “most significant advance since genetic fingerprinting”.

Criticism from Advisors and Monitors

Abimbola Johnson, head of the independent scrutiny and oversight board for the police race action plan, said: “We observed scant consideration in equality strategy sessions of the technology deployment despite obvious cross-over with the plan’s concerns.

“This disclosure show once again that the anti-racism commitments the police has undertaken via the equality initiative are not being translated into wider practice. Our reports have cautioned that new technologies are being rolled out in a landscape where ethnic inequalities, inadequate oversight and poor data collection already persist.

“Any use of facial recognition must adhere to rigorous official guidelines, be subject to external review, and prove it reduces rather than compounds racial disparity.”

Home Office Response

A Home Office spokesperson said: “We treat the findings of the study seriously and we have implemented changes. A new algorithm has been externally evaluated and acquired, which has no statistically significant bias. It will be tested early next year and will be undergo evaluation.

“Our priority is ensuring public safety. This revolutionary tool will support officers to put criminals and rapists behind bars. There is human involvement in every step of the process and no further action would be taken without trained officers carefully reviewing the results.”