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Law enforcement agencies across the UK successfully lobbied to deploy a facial recognition system known to be discriminatory against women, youths, and individuals from minority ethnic backgrounds, after complaining that a less biased version produced fewer potential suspects.

How the System Works

British police utilize the police national database (PND) to carry out searches using historical face recognition. This procedure involves matching 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 followed a study 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 “took steps on the findings”.

“It prompts the question of whether facial recognition only becomes useful if users accept biases in ethnicity and sex. Convenience is a weak argument for overriding fundamental rights.”

Long-Standing Problem

Official papers show that this bias has been known about for more than a year. Furthermore, police forces lobbied to reverse an initial decision that was designed to mitigate the problem.

Police bosses were informed of the system's bias in September 2024. The government-ordered laboratory study concluded the system was more likely to produce false positives for photos of women, individuals of Black ethnicity, and those under 40 years old.

A Policy U-Turn

In response, the national police leadership body mandated that the confidence threshold required for potential matches be increased to a point where the disparity was significantly reduced.

However, this decision was reversed the next month after forces complained that the adjusted system was producing a lower number of “useful lines of inquiry”. Internal records indicate the higher threshold reduced the proportion of searches that yielded potential matches from over half to a mere 14%.

Profound Inequalities

Although the authorities declined to specify what setting is currently used, the latest NPL study discovered the system could generate false positives for Black women nearly a hundred times more frequently than for Caucasian women at certain settings.

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

Balancing Utility and Fairness

Describing the effect of the brief increase to the system's accuracy setting, the police records note: “This adjustment greatly lessens the effect of bias across protected characteristics of race, generation and sex but had a significant negative impact on police efficiency”. The documents add that forces argued that “a previously useful tool returned results of questionable value”.

Broader Rollout Plans

Meanwhile, the government has opened a two-and-a-half-month public review on its plans to expand the use of facial recognition technology. The minister for police the relevant minister has labeled 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, said: “There was very little discussion through race action plan meetings of the facial recognition rollout despite clear relevance with the plan’s concerns.

“This disclosure show yet again that the anti-racism commitments policing has undertaken through the race action plan are not being translated into wider practice. Our reports have cautioned that new technologies are being rolled out in a context where ethnic inequalities, inadequate oversight and faulty information gathering already persist.

“Any use of facial recognition must meet strict national standards, be independently scrutinised, and prove it reduces rather than exacerbates ethnic bias.”

Official Statement

A government representative said: “We treat the conclusions of the report with utmost gravity and we have already taken action. A updated software has been externally evaluated and procured, which has no statistically significant bias. It will be tested early next year and will be subject to evaluation.

“The foremost aim is ensuring public safety. This gamechanging technology will support police to put criminals and rapists behind bars. There is officer review in every step of the process and no further action would be pursued without specialist personnel meticulously examining the results.”