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Police forces across the United Kingdom effectively campaigned to use a facial recognition system known to be biased against women, young people, and individuals from ethnic minority groups, following complaints that a more accurate version produced fewer investigative leads.

How the System Works

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

Admitted Bias

The UK interior ministry admitted last week that the system was flawed. This admission followed a review by the government's National Physical Laboratory determined it incorrectly matched people of Black and Asian heritage and women at much greater frequency than Caucasian males. The Home Office said it “had acted on the findings”.

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

Known Issue

Official papers reveal that this discriminatory flaw has been known about for more than a year. Furthermore, police forces argued to overturn an earlier ruling that was intended to mitigate the problem.

Police bosses were informed of the system's bias in late 2024. The Home Office-commissioned laboratory study concluded the system was more likely to produce incorrect matches for images depicting women, Black people, and those aged 40 and under.

A Reversed Decision

In reaction, the National Police Chiefs’ Council (NPCC) ordered that the accuracy setting required for possible hits 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”. Internal records show the higher threshold reduced the proportion of queries that yielded possible identifications from over half to a just 14%.

Severe Disparities

Although the authorities refused to say what threshold is now in operation, the latest NPL study discovered 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 commented on these results: “The testing found that in a specific scenarios the algorithm is has a greater tendency to wrongly flag some demographic groups in its match reports.”

Balancing Utility and Fairness

Outlining the impact of the brief increase to the system's accuracy setting, the NPCC documents note: “This adjustment significantly reduces the effect of bias across protected characteristics of ethnicity, age and gender but had a significant negative impact on operational effectiveness”. The documents further note that police units argued that “a previously useful tool returned outcomes of limited benefit”.

Broader Rollout Plans

Meanwhile, the UK administration has launched a ten-week consultation on its proposals to expand the use of facial recognition technology. The minister for police the relevant minister has described the tool as the “most significant advance since DNA matching”.

Criticism from Advisors and Monitors

The chair of a police oversight board, head of the independent scrutiny and oversight board for the police race action plan, said: “There was very little consideration in equality strategy sessions of the facial recognition rollout despite obvious cross-over with the strategy's goals.

“These revelations show once again that the pledges to combat discrimination the police has made via the equality initiative are not being translated into broader operations. Independent assessments have warned that innovative tools are being rolled out in a context where ethnic inequalities, weak scrutiny and poor data collection already persist.

“Any use of this technology must adhere to rigorous official guidelines, be subject to external review, and prove it reduces rather than compounds racial disparity.”

Official Statement

A Home Office spokesperson said: “We treat the findings of the report with utmost gravity and we have already taken action. A new algorithm has been externally evaluated and procured, which has demonstrated no measurable discrimination. It will be trialled in the coming months and will be undergo further assessment.

“Our priority is ensuring public safety. This gamechanging technology will assist officers to apprehend and prosecute offenders. There is officer review in each stage of the procedure and no arrest or charge would be pursued without specialist personnel meticulously examining the results.”