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Law enforcement agencies across the UK successfully lobbied to deploy a facial recognition system known to be discriminatory against women, young people, and members of ethnic minority groups, after complaining that a less biased version produced a reduced number of potential suspects.

The Technology in Practice

British police utilize the national police database to carry out retrospective facial recognition searches. This process involves matching a reference photograph of a suspect against a repository of more than 19 million custody photos to find possible hits.

Acknowledged Discrimination

The Home Office conceded last week that the technology was biased. This admission came after a review by the National Physical Laboratory (NPL) found it incorrectly matched people of Black and Asian heritage and women at much greater frequency than Caucasian males. The Home Office stated it “took steps on the findings”.

“This raises the question of whether facial recognition only becomes effective if users tolerate discrimination in race and gender. Convenience is a poor argument for overriding basic freedoms.”

Known Issue

Internal documents show that this discriminatory flaw has been known about for over twelve months. Furthermore, law enforcement argued to overturn an initial decision that was designed to address the problem.

Police bosses were informed of the system's bias in September 2024. The government-ordered 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 reaction, the national police leadership body ordered that the confidence threshold required for possible hits be raised to a level where the disparity was greatly diminished.

However, this decision was overturned the following month after forces complained that the adjusted system was generating a lower number of “investigative leads”. Internal records indicate the higher threshold cut the proportion of searches that yielded possible identifications from over half to a just under 15%.

Severe Disparities

Although the Home Office and NPCC declined to specify what setting is currently used, the recent independent review found the system could produce false positives for women of Black heritage nearly a hundred times more often than for Caucasian women at specific configurations.

The ministry commented on these results: “Our evaluation found that in a specific scenarios 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 temporary raise to the system's accuracy setting, the NPCC documents note: “The change significantly reduces the impact of bias across protected characteristics of ethnicity, age and sex but had a substantially detrimental effect on police efficiency”. The documents add that police units argued that “a previously useful tool now delivered results of limited benefit”.

Broader Rollout Plans

Meanwhile, the government has launched a two-and-a-half-month public review on its plans to expand the use of biometric scanning systems. The minister for police Sarah Jones has labeled the tool as the “most significant advance since DNA matching”.

Criticism from Advisors and Monitors

Abimbola Johnson, chair of the advisory panel for the police race action plan, commented: “We observed very little consideration in equality strategy sessions of the technology deployment even with obvious cross-over with the strategy's goals.

“These revelations show yet again that the anti-racism commitments policing has undertaken via the equality initiative are failing to be integrated into wider practice. Our reports have warned that new technologies are being rolled out in a context where ethnic inequalities, weak scrutiny and faulty information gathering already persist.

“All deployment of facial recognition must adhere to strict national standards, 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 report seriously and we have implemented changes. A updated software has been independently tested and procured, which has demonstrated no measurable discrimination. It will be trialled in the coming months and will be subject to further assessment.

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