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Police forces across the UK successfully lobbied to deploy a facial recognition system known to be biased against women, youths, and individuals from minority ethnic backgrounds, following complaints that a less biased version generated fewer investigative leads.

How the System Works

UK forces utilize the national police database to carry out searches using historical face recognition. This procedure entails comparing a reference photograph of a suspect 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 technology was biased. This acknowledgment came after a review by the National Physical Laboratory (NPL) found it incorrectly matched Black and Asian people and women at significantly higher rates than white men. The Home Office stated it “had acted on the findings”.

“It prompts the question of whether facial recognition only becomes effective if users tolerate biases in race and gender. Operational ease is a weak argument for disregarding fundamental rights.”

Long-Standing Problem

Internal documents show that this bias has been known about for more than a year. Furthermore, police forces argued to overturn an initial decision that was designed to address the problem.

Police bosses were informed of the system's bias in late 2024. The Home Office-commissioned NPL review concluded the system was more likely to produce false positives for photos of females, Black people, and those under 40 years old.

A Reversed Decision

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

However, this decision was reversed the next month after forces complained that the adjusted system was producing a lower number of “investigative leads”. NPCC documents indicate the higher threshold reduced the number of queries that yielded possible identifications from 56% to a just under 15%.

Profound Inequalities

Although the Home Office and NPCC declined to specify what setting is now in operation, the recent independent review discovered the system could generate false positives for women of Black heritage almost 100 times more often than for white women at specific configurations.

The ministry commented on these results: “Our evaluation identified that in a limited set of circumstances the software is more likely to wrongly flag some demographic groups in its search results.”

Balancing Utility and Fairness

Outlining the impact of the brief increase to the system's confidence threshold, the police records note: “This adjustment significantly reduces the impact of bias across protected characteristics of ethnicity, age and sex but had a substantially detrimental effect on operational effectiveness”. The papers further note that forces complained that “a once effective tactic returned outcomes of questionable value”.

Broader Rollout Plans

Meanwhile, the government has opened a two-and-a-half-month consultation on its plans to expand the use of biometric scanning systems. Policing minister the relevant minister has described the technology as the “biggest breakthrough since DNA matching”.

Criticism from Advisors and Monitors

The chair of a police oversight board, head of the advisory panel for the national policing equality strategy, said: “We observed very little consideration in race action plan meetings of the technology deployment despite obvious cross-over with the strategy's goals.

“These revelations show yet again that the anti-racism commitments the police has undertaken through the equality initiative are not being translated into broader operations. Independent assessments have cautioned that innovative tools are being rolled out in a context where ethnic inequalities, weak scrutiny and poor data collection already persist.

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

Home Office Response

A government representative stated: “The Home Office takes the conclusions of the report seriously and we have already taken action. A new algorithm has been externally evaluated and acquired, which has no statistically significant bias. It will be trialled in the coming months and will be subject to further assessment.

“The foremost aim is ensuring public safety. This revolutionary tool will support police to put criminals and rapists behind bars. There is human involvement in every step of the process and no arrest or charge would be taken without trained officers meticulously examining the output.”