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Police forces across the United Kingdom effectively campaigned to use a facial recognition system known to be discriminatory against women, youths, and members of minority ethnic backgrounds, after complaining that a more accurate version produced fewer investigative leads.

The Technology in Practice

British police use the national police database to carry out retrospective facial recognition searches. This procedure entails matching a reference photograph of a suspect against a database of over 19 million mugshots to find potential matches.

Admitted Bias

The Home Office conceded last week that the technology was flawed. This acknowledgment came after a study by the government's National Physical Laboratory determined it incorrectly matched people of Black and Asian heritage and females at much greater frequency than white men. The Home Office stated it “had acted on the findings”.

“This raises the question of whether facial recognition only becomes useful if users accept discrimination in ethnicity and sex. Convenience is a poor argument for overriding fundamental rights.”

Long-Standing Problem

Internal documents reveal that this bias has been recognized for over twelve months. Furthermore, police forces argued to overturn an earlier ruling that was designed to mitigate the problem.

Police bosses were notified of the system's bias in late 2024. The Home Office-commissioned laboratory study concluded the system was more likely to suggest false positives for images depicting females, Black people, and those under 40 years old.

A Reversed Decision

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

However, this directive was overturned the next month following complaints from police that the adjusted system was producing fewer “investigative leads”. NPCC documents indicate the higher threshold reduced the proportion of queries that yielded potential matches from 56% to a just 14%.

Severe Disparities

Although the authorities refused to say what threshold is now in operation, the latest NPL study found the system could produce incorrect matches for Black women nearly a hundred times more frequently than for Caucasian women at specific configurations.

The Home Office commented on these results: “Our evaluation found that in a specific scenarios the algorithm is more likely to wrongly flag some population segments in its search results.”

Balancing Utility and Fairness

Outlining the effect of the temporary raise to the system's accuracy setting, the NPCC documents state: “This adjustment greatly lessens the effect of bias across protected characteristics of ethnicity, age and gender but had a significant negative impact on police efficiency”. The papers further note that police units complained that “a once effective tactic returned results of limited benefit”.

Wider Implementation Proposals

Meanwhile, the government has opened a ten-week public review on its plans to widen the use of facial recognition technology. The minister for police the relevant minister has described the technology as the “most significant advance since DNA matching”.

Criticism from Advisors and Monitors

Abimbola Johnson, chair of the advisory panel for the national policing equality strategy, said: “We observed very little consideration through equality strategy sessions of the facial recognition rollout even with obvious cross-over with the strategy's goals.

“This disclosure demonstrate yet again that the anti-racism commitments policing has made via the race action plan are failing to be integrated into broader operations. Independent assessments have warned that innovative tools are being rolled out in a context where ethnic inequalities, weak scrutiny and faulty information gathering already persist.

“All deployment of this technology must adhere to strict national standards, be subject to external review, and prove it diminishes rather than compounds racial disparity.”

Official Statement

A Home Office spokesperson said: “The Home Office takes the findings of the report seriously and we have implemented changes. A new algorithm has been independently tested and procured, which has no statistically significant bias. It will be trialled early next year and will be undergo evaluation.

“The foremost aim is protecting the public. This gamechanging technology will assist officers to apprehend and prosecute offenders. There is officer review in each stage of the process and no further action would be pursued without trained officers meticulously examining the results.”