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Police forces across the UK effectively campaigned to deploy a face scanning system acknowledged as discriminatory against females, youths, and individuals from ethnic minority groups, following complaints that a less biased version produced a reduced number of potential suspects.

The Technology in Practice

UK forces use the national police database to carry out searches using historical face recognition. This procedure involves matching a reference photograph of a suspect against a database of over 19 million custody photos to identify potential matches.

Admitted Bias

The Home Office conceded last week that the technology was flawed. This acknowledgment followed a review by the government's National Physical Laboratory found it incorrectly matched 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 question of whether this technology only becomes useful if users tolerate biases in ethnicity and sex. Operational ease is a poor argument for overriding basic freedoms.”

Long-Standing Problem

Internal documents reveal that this bias has been known about for more than a year. Furthermore, police forces lobbied to reverse an initial decision that was designed to mitigate 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 suggest incorrect matches for images depicting females, individuals of Black ethnicity, and those under 40 years old.

A Policy U-Turn

In reaction, the national police leadership body mandated that the confidence threshold required for possible hits be increased to a point where the bias was greatly diminished.

However, this decision was reversed the following month after forces complained that the modified technology was generating fewer “investigative leads”. NPCC documents show the stricter setting reduced the proportion of queries resulting in potential matches from over half to a mere under 15%.

Profound Inequalities

Although the authorities refused to say what threshold is currently used, the recent NPL study found the system could generate incorrect matches for Black women nearly a hundred times more frequently than for Caucasian women at specific configurations.

The ministry commented on these findings: “Our evaluation found that in a specific scenarios the algorithm is more likely to incorrectly include some population segments in its search results.”

Operational Effectiveness vs. Bias

Outlining the impact of the brief increase to the system's accuracy setting, the NPCC documents state: “The change significantly reduces the impact of discrimination across protected characteristics of race, generation and gender but had a significant negative impact on operational effectiveness”. The papers add that police units complained that “a once effective tactic returned outcomes of limited benefit”.

Broader Rollout Plans

Meanwhile, the government has opened a ten-week consultation on its proposals to expand the use of biometric scanning systems. Policing minister the relevant minister has labeled the tool as the “biggest breakthrough since genetic fingerprinting”.

Criticism from Advisors and Monitors

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

“This disclosure show once again that the anti-racism commitments the police has made through the race action plan are failing to be integrated 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 continue to exist.

“All deployment of facial recognition must meet strict national standards, be subject to external review, and demonstrate it reduces rather than exacerbates racial disparity.”

Official Statement

A government representative said: “The Home Office treat the conclusions of the report with utmost gravity and we have already taken action. A updated software has been independently tested and procured, which has no statistically significant bias. It will be trialled in the coming months and will be undergo evaluation.

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