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Police forces across the UK effectively campaigned to use a facial recognition system known to be biased against females, youths, and members of ethnic minority groups, following complaints that a more accurate version produced a reduced number of potential suspects.

The Technology in Practice

UK forces utilize the national police database to carry out retrospective facial recognition searches. This procedure entails comparing a reference photograph of a suspect against a database of more than 19 million custody photos to identify possible hits.

Admitted Bias

The Home Office conceded last week that the system was biased. This admission came after a study by the government's National Physical Laboratory determined it incorrectly matched Black and Asian people and women at significantly higher rates than Caucasian males. The Home Office stated it “took steps on the findings”.

“It prompts the issue of whether this technology only becomes effective if users tolerate biases in race and sex. Operational ease is a weak argument for overriding basic freedoms.”

Long-Standing Problem

Official papers reveal that this bias has been known about for more than a year. Furthermore, law enforcement lobbied to reverse an earlier ruling that was intended to address the problem.

Senior officers were informed of the algorithmic discrimination in September 2024. The Home Office-commissioned laboratory study found the system was more likely to suggest incorrect matches for images depicting women, Black people, and those aged 40 and under.

A Policy U-Turn

In reaction, the National Police Chiefs’ Council (NPCC) ordered that the confidence threshold required for possible hits be raised to a point where the bias was greatly diminished.

However, this decision was overturned the following month following complaints from police that the modified technology was producing a lower number of “useful lines of inquiry”. NPCC documents indicate the higher threshold reduced the number of queries that yielded potential matches from 56% to a mere under 15%.

Severe Disparities

Although the authorities declined to specify what threshold is currently used, the latest NPL study discovered the system could produce incorrect matches for women of Black heritage almost 100 times more often than for Caucasian women at certain settings.

The ministry commented on these findings: “Our evaluation identified that in a limited set of circumstances the algorithm is has a greater tendency to wrongly flag some population segments in its match reports.”

Balancing Utility and Fairness

Outlining the effect of the brief increase to the system's confidence threshold, the police records note: “The change significantly reduces the effect of discrimination across protected characteristics of race, age and sex but had a substantially detrimental effect on police efficiency”. The documents add that forces complained that “a once effective tactic returned outcomes of questionable value”.

Wider Implementation Proposals

Meanwhile, the UK administration has launched a ten-week consultation on its plans to expand the use of facial recognition technology. The minister for police Sarah Jones has described the tool as the “biggest breakthrough since DNA matching”.

Expert and Oversight Concerns

Abimbola Johnson, head of the independent scrutiny and oversight board for the police race action plan, commented: “There was scant consideration in race action plan meetings of the facial recognition rollout despite clear relevance with the strategy's goals.

“These revelations demonstrate once again that the anti-racism commitments policing has made via the race action plan are failing to be integrated into broader operations. Our reports have cautioned that new technologies are being rolled out in a context where racial disparities, weak scrutiny and faulty information gathering already persist.

“Any use of this technology must meet rigorous official guidelines, be independently scrutinised, and demonstrate it reduces rather than compounds racial disparity.”

Home Office Response

A Home Office spokesperson said: “We takes the findings of the report seriously and we have implemented changes. A new algorithm has been independently tested and acquired, which has demonstrated no measurable discrimination. It will be trialled early next year and will be subject to further assessment.

“The foremost aim 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 process and no further action would be pursued without trained officers carefully reviewing the output.”