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Police forces across the UK effectively campaigned to deploy a facial recognition system acknowledged as biased against women, youths, and members of minority ethnic backgrounds, after complaining that a less biased version generated fewer investigative leads.

The Technology in Practice

UK forces utilize the national police database to carry out retrospective facial recognition searches. This process involves matching a reference photograph of a person of interest against a repository of over 19 million custody photos to identify potential matches.

Acknowledged Discrimination

The Home Office admitted last week that the system was flawed. This admission followed a review by the government's National Physical Laboratory found it incorrectly matched Black and Asian people and females at much greater frequency than Caucasian males. The ministry stated it “had acted on the findings”.

“This raises the issue of whether facial recognition only becomes useful if users tolerate biases in ethnicity and sex. Convenience is a poor argument for disregarding fundamental rights.”

Known Issue

Official papers reveal that this bias has been known about for over twelve months. Furthermore, law enforcement lobbied to reverse an initial decision that was designed to address the problem.

Police bosses were informed of the system's bias in late 2024. The Home Office-commissioned NPL review concluded the system was more likely to suggest incorrect matches for images depicting women, individuals of Black ethnicity, and those under 40 years old.

A Policy U-Turn

In reaction, the National Police Chiefs’ Council (NPCC) ordered that the confidence threshold required for potential matches be increased to a level where the disparity was significantly reduced.

However, this decision was overturned the following month following complaints from police that the modified technology was producing a lower number of “investigative leads”. Internal records indicate the higher threshold reduced the proportion of searches that yielded potential matches from over half to a mere under 15%.

Profound Inequalities

Although the authorities declined to specify what threshold is now in operation, the latest NPL study found the system could produce incorrect matches for women of Black heritage almost 100 times more frequently than for white women at certain settings.

The ministry stated on these results: “The testing identified that in a limited set of circumstances the algorithm is more likely to wrongly flag some population segments in its search results.”

Balancing Utility and Fairness

Outlining the effect of the brief increase to the system's accuracy setting, the NPCC documents note: “This adjustment greatly lessens the impact of discrimination across legally safeguarded attributes of ethnicity, generation and gender but had a significant negative impact on police efficiency”. The documents add that forces argued that “a previously useful tool now delivered outcomes of questionable value”.

Wider Implementation Proposals

Meanwhile, the UK administration has opened a two-and-a-half-month consultation on its plans to widen the use of facial recognition technology. The minister for police Sarah Jones has described the tool as the “most significant advance since DNA matching”.

Criticism from Advisors and Monitors

Abimbola Johnson, head of the advisory panel for the national policing equality strategy, said: “We observed scant consideration in equality strategy sessions of the facial recognition rollout despite obvious cross-over with the plan’s concerns.

“This disclosure show once again that the pledges to combat discrimination policing has made via the race action plan are not being translated into broader operations. Independent assessments have warned that innovative tools are being implemented in a context where ethnic inequalities, inadequate oversight and faulty information gathering continue to exist.

“All deployment of facial recognition must meet strict national standards, be subject to external review, and demonstrate it diminishes rather than compounds ethnic bias.”

Official Statement

A Home Office spokesperson said: “We treat the conclusions of the report seriously and we have implemented changes. A new algorithm has been externally evaluated and acquired, which has demonstrated no measurable discrimination. It will be tested early next year and will be undergo further assessment.

“Our priority is protecting the public. This gamechanging technology will assist police to apprehend and prosecute offenders. There is human involvement in every step of the process and no arrest or charge would be taken without specialist personnel meticulously examining the results.”