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Law enforcement agencies across the UK successfully lobbied to deploy a face scanning system acknowledged as biased against females, young people, and individuals from ethnic minority groups, following complaints that a more accurate version produced a reduced number of investigative leads.

How the System Works

British police utilize the police national database (PND) to conduct searches using historical face recognition. This process involves comparing a “probe image” of a person of interest against a database 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 study by the National Physical Laboratory (NPL) determined it incorrectly matched people of Black and Asian heritage and females at much greater frequency than Caucasian males. The Home Office said it “took steps on the findings”.

“It prompts the question of whether this technology only becomes effective if users tolerate discrimination in race and sex. Convenience is a poor argument for disregarding fundamental rights.”

Known Issue

Official papers show that this discriminatory flaw has been recognized 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 September 2024. The government-ordered laboratory study found the system was had a higher probability to produce incorrect matches for photos of females, Black people, and those under 40 years old.

A Reversed Decision

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

However, this decision was overturned the following month following complaints from police that the adjusted system was generating fewer “useful lines of inquiry”. Internal records indicate the stricter setting reduced the proportion of searches resulting in potential matches from over half to a mere under 15%.

Profound Inequalities

Although the authorities refused to say what setting is now in operation, the recent NPL study discovered the system could produce false positives for women of Black heritage almost 100 times more frequently than for white women at specific configurations.

The Home Office commented on these findings: “The testing found that in a specific scenarios the algorithm is more likely to incorrectly include some population segments in its match reports.”

Balancing Utility and Fairness

Outlining the impact of the temporary raise to the system's confidence threshold, the NPCC documents state: “The change significantly reduces the impact of bias across legally safeguarded attributes of race, generation and sex but had a significant negative impact on police efficiency”. The documents further note that police units complained that “a previously useful tool now delivered results of questionable value”.

Broader Rollout Plans

Meanwhile, the government has opened a ten-week public review on its plans to expand the use of facial recognition technology. Policing minister Sarah Jones has described the tool as the “most significant advance since DNA matching”.

Criticism from Advisors and Monitors

The chair of a police oversight board, head of the independent scrutiny and oversight board for the police race action plan, said: “We observed very little discussion through race action plan meetings of the facial recognition rollout despite obvious cross-over with the plan’s concerns.

“These revelations demonstrate once again that the pledges to combat discrimination policing has made through the race action plan are failing to be integrated into wider practice. Our reports have cautioned that new technologies are being implemented in a landscape where ethnic inequalities, inadequate oversight and poor data collection continue to exist.

“Any use of facial recognition must meet rigorous official guidelines, be subject to external review, and demonstrate it reduces rather than exacerbates ethnic bias.”

Home Office Response

A government representative said: “We treat the findings of the report seriously and we have already taken action. A new algorithm has been independently tested and procured, which has no statistically significant bias. It will be tested in the coming months and will be subject to evaluation.

“Our priority is ensuring public safety. This gamechanging technology will assist officers to put criminals and rapists behind bars. There is officer review in every step of the procedure and no further action would be taken without specialist personnel meticulously examining the output.”