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Police forces across the UK successfully lobbied 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 generated fewer investigative leads.

How the System Works

British police utilize the national police database to carry out searches using historical face recognition. This procedure involves matching a “probe image” of a suspect against a repository of more than 19 million custody photos to identify possible hits.

Acknowledged Discrimination

The Home Office admitted last week that the system was biased. This acknowledgment followed a review by the National Physical Laboratory (NPL) determined it misidentified Black and Asian people and females at significantly higher rates than white men. The ministry stated it “had acted on the findings”.

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

Known Issue

Internal documents show that this bias has been recognized for more than a year. Furthermore, police forces lobbied to reverse an initial decision that was designed to address the problem.

Police bosses were notified of the system's bias in late 2024. The government-ordered laboratory study found the system was more likely to produce incorrect matches for images depicting women, individuals of Black ethnicity, and those under 40 years old.

A Reversed Decision

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

However, this decision was reversed the next month after forces complained that the modified technology was generating a lower number of “investigative leads”. Internal records indicate the higher threshold reduced the number of queries resulting in potential matches from 56% 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 generate false positives for Black women almost 100 times more often than for white women at certain settings.

The ministry commented on these results: “The testing identified that in a limited set of circumstances the software is has a greater tendency to wrongly flag some population segments in its search results.”

Operational Effectiveness vs. Bias

Describing the effect of the brief increase to the system's accuracy setting, the police records state: “This adjustment significantly reduces the impact of bias across legally safeguarded attributes of ethnicity, generation and gender but had a significant negative impact on police efficiency”. The documents further note that police units complained that “a previously useful tool now delivered results of questionable value”.

Broader Rollout Plans

Meanwhile, the government has launched a two-and-a-half-month consultation on its proposals to expand the use of biometric scanning systems. The minister for police the relevant minister has labeled the tool as the “biggest breakthrough since DNA matching”.

Criticism from Advisors and Monitors

Abimbola Johnson, chair of the advisory panel for the police race action plan, commented: “There was very little consideration through equality strategy sessions of the facial recognition rollout despite obvious cross-over with the strategy's goals.

“These revelations demonstrate once again that the pledges to combat discrimination the police has undertaken via the race action plan are failing to be integrated into wider practice. Independent assessments have cautioned that new technologies are being implemented in a context where ethnic inequalities, inadequate oversight and poor data collection already persist.

“Any use of facial recognition must adhere to rigorous official guidelines, be subject to external review, and prove it reduces rather than exacerbates ethnic bias.”

Home Office Response

A government representative stated: “We treat the findings of the study with utmost gravity and we have implemented changes. A updated software has been independently tested and procured, which has demonstrated no measurable discrimination. It will be tested early next year and will be subject to further assessment.

“Our priority is ensuring public safety. This revolutionary tool will support officers to apprehend and prosecute offenders. There is human involvement in every step of the procedure and no further action would be pursued without trained officers carefully reviewing the output.”