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Police forces across the UK successfully lobbied to deploy a facial recognition system acknowledged as biased against females, youths, and individuals from minority ethnic backgrounds, after complaining that a more accurate version produced fewer investigative leads.

How the System Works

British police use the national police database to conduct retrospective facial recognition searches. This process entails matching a reference photograph of a person of interest against a database of more than 19 million custody photos to identify possible hits.

Admitted Bias

The UK interior ministry conceded last week that the system was biased. This admission followed a study by the government's National Physical Laboratory determined it incorrectly matched Black and Asian people and females at much greater frequency than white men. The Home Office stated it “had acted on the findings”.

“This raises the issue of whether facial recognition only becomes useful if users accept discrimination in race and sex. Convenience is a weak argument for disregarding basic freedoms.”

Known Issue

Internal documents reveal that this discriminatory flaw has been known about for over twelve months. Furthermore, police forces argued to overturn an initial decision that was designed to mitigate the problem.

Police bosses were informed of the algorithmic discrimination in September 2024. The government-ordered NPL review found the system was had a higher probability to suggest incorrect matches for photos of women, Black people, and those under 40 years old.

A Reversed Decision

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

However, this decision was overturned the next month following complaints from police that the adjusted system was generating fewer “investigative leads”. NPCC documents show the higher threshold cut the proportion of searches resulting in potential matches from 56% to a mere under 15%.

Severe Disparities

Although the authorities refused to say what threshold is now in operation, the latest independent review found the system could generate incorrect matches for women of Black heritage nearly a hundred times more frequently than for Caucasian women at certain settings.

The Home Office stated on these findings: “The testing identified that in a specific scenarios the algorithm is has a greater tendency to incorrectly include some demographic groups in its search results.”

Balancing Utility and Fairness

Describing the effect of the temporary raise to the system's accuracy setting, the police records note: “The change greatly lessens the effect of bias across legally safeguarded attributes of race, generation and gender but had a substantially detrimental effect on police efficiency”. The documents further note that police units complained that “a once effective tactic now delivered results of limited benefit”.

Wider Implementation Proposals

Meanwhile, the UK administration has opened a ten-week consultation on its plans to expand the use of facial recognition technology. Policing minister the relevant minister has labeled the tool as the “biggest breakthrough since genetic fingerprinting”.

Criticism from Advisors and Monitors

Abimbola Johnson, head of the independent scrutiny and oversight board for the police race action plan, commented: “We observed very little consideration in race action plan meetings of the technology deployment despite clear relevance with the strategy's goals.

“This disclosure show once again that the pledges to combat discrimination the police has made via the equality initiative are failing to be integrated into wider practice. Our reports have warned that innovative tools are being rolled out in a landscape where ethnic inequalities, inadequate oversight and faulty information gathering continue to exist.

“Any use of this technology must adhere to strict national standards, be subject to external review, and demonstrate it diminishes rather than compounds ethnic bias.”

Home Office Response

A Home Office spokesperson said: “The Home Office treat the conclusions of the report with utmost gravity and we have already taken action. A new algorithm has been independently tested and acquired, which has no statistically significant bias. It will be trialled early next year and will be undergo further assessment.

“The foremost aim is ensuring public safety. This revolutionary tool will assist police to put criminals and rapists behind bars. There is officer review in every step of the process and no further action would be taken without trained officers meticulously examining the output.”