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Police forces across the UK effectively campaigned to deploy a facial recognition system acknowledged as discriminatory against females, young people, and individuals from ethnic minority groups, after complaining that a more accurate version produced a reduced number of potential suspects.

How the System Works

British police utilize the police national database (PND) to conduct searches using historical face recognition. This procedure entails matching a “probe image” of a suspect against a database of more than 19 million mugshots to identify possible hits.

Acknowledged Discrimination

The UK interior ministry conceded last week that the technology was flawed. This admission followed a review by the government's National Physical Laboratory found it incorrectly matched Black and Asian people and females at significantly higher rates than Caucasian males. The ministry said it “had acted on the findings”.

“This raises the issue of whether this technology only becomes useful if users accept discrimination in ethnicity and gender. Operational ease is a weak argument for disregarding fundamental rights.”

Known Issue

Official papers show that this bias has been known about for over twelve months. Furthermore, law enforcement lobbied to reverse an initial decision that was designed to address the problem.

Police bosses were informed of the system's bias in September 2024. The Home Office-commissioned NPL review concluded the system was had a higher probability to produce false positives for images depicting women, Black people, and those under 40 years old.

A Reversed Decision

In response, the National Police Chiefs’ Council (NPCC) mandated that the accuracy setting required for possible hits be raised to a level where the bias was significantly reduced.

However, this directive was reversed the next month following complaints from police that the adjusted system was generating a lower number of “useful lines of inquiry”. NPCC documents show the higher threshold reduced the proportion of queries that yielded potential matches from 56% to a mere under 15%.

Profound Inequalities

Although the authorities refused to say what threshold is now in operation, the latest NPL study found the system could generate incorrect matches for Black women almost 100 times more frequently than for Caucasian women at specific configurations.

The ministry stated on these findings: “The testing identified that in a limited set of circumstances the algorithm is has a greater tendency to incorrectly include some population segments in its search results.”

Operational Effectiveness vs. Bias

Outlining the effect of the temporary raise to the system's confidence threshold, the NPCC documents state: “This adjustment significantly reduces the impact of bias across protected characteristics of ethnicity, generation and gender but had a significant negative impact on police efficiency”. The papers add that police units argued that “a once effective tactic now delivered outcomes of limited benefit”.

Broader Rollout Plans

Meanwhile, the UK administration has opened a two-and-a-half-month public review on its proposals to widen the use of facial recognition technology. The minister for police Sarah Jones has labeled the technology as the “biggest breakthrough since DNA matching”.

Expert and Oversight Concerns

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

“This disclosure demonstrate yet again that the anti-racism commitments the police has made through the race action plan are not being translated into wider practice. Our reports have warned that innovative tools are being rolled out in a context where racial disparities, weak scrutiny and faulty information gathering already persist.

“All deployment of facial recognition must meet rigorous official guidelines, be independently scrutinised, and prove it diminishes rather than compounds ethnic bias.”

Official Statement

A government representative said: “The Home Office treat the conclusions of the report with utmost gravity and we have implemented changes. A new algorithm has been independently tested and acquired, which has no statistically significant bias. It will be trialled in the coming months and will be undergo evaluation.

“The foremost aim is protecting the public. This revolutionary tool will support police to put criminals and rapists behind bars. There is officer review in every step of the procedure and no arrest or charge would be pursued without specialist personnel carefully reviewing the output.”