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Police forces across the United Kingdom effectively campaigned to use a facial recognition system acknowledged as biased against women, young people, and members of minority ethnic backgrounds, after complaining that a more accurate version produced fewer potential suspects.

How the System Works

UK forces utilize the police national database (PND) to conduct searches using historical face recognition. This procedure involves matching a reference photograph of a person of interest against a database of more than 19 million custody photos to find potential matches.

Admitted Bias

The UK interior ministry conceded last week that the system was flawed. This admission came after a study by the government's National Physical Laboratory found it misidentified people of Black and Asian heritage and females at significantly higher rates than Caucasian males. The ministry said it “took steps on the findings”.

“This raises the issue of whether facial recognition only becomes useful if users tolerate biases in race and sex. Operational ease is a poor argument for disregarding fundamental rights.”

Known Issue

Official papers show 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 concluded the system was had a higher probability to produce false positives for images depicting females, Black people, and those aged 40 and under.

A Policy U-Turn

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

However, this directive was overturned the following month following complaints from police that the modified technology was producing a lower number of “useful lines of inquiry”. Internal records indicate the higher threshold reduced the number of queries resulting in potential matches from over half to a mere under 15%.

Severe Disparities

Although the authorities declined to specify what threshold is now in operation, the recent NPL study discovered the system could produce incorrect matches for women of Black heritage almost 100 times more often than for Caucasian women at certain settings.

The ministry stated on these findings: “Our evaluation found 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 brief increase to the system's confidence threshold, the NPCC documents note: “The change significantly reduces the effect of bias across protected characteristics of race, generation and sex but had a substantially detrimental effect on police efficiency”. The documents further note that forces argued that “a once effective tactic now delivered results of questionable value”.

Wider Implementation Proposals

Meanwhile, the government has opened a ten-week consultation on its proposals to expand the use of facial recognition technology. Policing minister the relevant minister has labeled the tool as the “biggest breakthrough since DNA matching”.

Expert and Oversight Concerns

The chair of a police oversight board, head of the advisory panel for the police race action plan, said: “There was scant consideration through race action plan meetings of the facial recognition rollout despite obvious cross-over with the plan’s concerns.

“These revelations show yet again that the anti-racism commitments the police has made through the race action plan are not being translated into wider practice. Independent assessments have warned that innovative tools are being rolled out in a landscape where racial disparities, weak scrutiny and faulty information gathering already persist.

“All deployment of this technology must adhere to strict national standards, be independently scrutinised, and demonstrate it reduces rather than exacerbates racial disparity.”

Official Statement

A Home Office spokesperson stated: “The Home Office takes the findings of the report with utmost gravity and we have implemented changes. A new algorithm has been independently tested and acquired, which has demonstrated no measurable discrimination. It will be trialled in the coming months and will be undergo evaluation.

“Our priority is ensuring public safety. This revolutionary tool will assist police to put criminals and rapists behind bars. There is human involvement in each stage of the procedure and no arrest or charge would be pursued without specialist personnel meticulously examining the results.”