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Law enforcement agencies across the UK effectively campaigned to deploy a face scanning system known to be discriminatory against women, youths, and members of minority ethnic backgrounds, following complaints that a more accurate version produced a reduced number of investigative leads.

How the System Works

British police use the national police database to conduct searches using historical face recognition. This process involves comparing a “probe image” of a person of interest against a database of more than 19 million custody photos to find possible hits.

Acknowledged Discrimination

The Home Office admitted last week that the system was biased. This admission came after a study by the National Physical Laboratory (NPL) determined it misidentified Black and Asian people and females at much greater frequency than white men. The ministry said it “took steps on the findings”.

“This raises the issue of whether this technology only becomes effective if users accept discrimination in ethnicity and sex. Operational ease is a poor argument for overriding fundamental rights.”

Long-Standing Problem

Official papers reveal that this discriminatory flaw has been known about for more than a year. Furthermore, law enforcement argued to overturn an initial decision that was designed to mitigate the problem.

Senior officers were informed of the algorithmic discrimination in September 2024. The Home Office-commissioned laboratory study concluded the system was more likely to produce incorrect matches for photos of women, Black people, 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 disparity was greatly diminished.

However, this directive was overturned the following month after forces complained that the modified technology was generating a lower number of “investigative leads”. NPCC documents show the higher threshold reduced the number of queries that yielded possible identifications from over half to a mere under 15%.

Profound Inequalities

Although the authorities declined to specify what threshold is now in operation, the recent NPL study found the system could generate false positives for women of Black heritage nearly a hundred times more often than for Caucasian women at certain settings.

The ministry stated on these results: “Our evaluation found that in a specific scenarios the algorithm is has a greater tendency to wrongly flag some population segments in its search results.”

Operational Effectiveness vs. Bias

Outlining the impact of the brief increase to the system's confidence threshold, the police records state: “The change significantly reduces the effect of bias across legally safeguarded attributes of ethnicity, generation and sex but had a significant negative impact on police efficiency”. The papers add that forces argued that “a previously useful tool now delivered outcomes of limited benefit”.

Broader Rollout Plans

Meanwhile, the government has launched a ten-week public review on its plans to widen the use of biometric scanning systems. The minister for police Sarah Jones has described the technology as the “biggest breakthrough since genetic fingerprinting”.

Criticism from Advisors and Monitors

The chair of a police oversight board, chair of the independent scrutiny and oversight board for the police race action plan, said: “There was very little consideration through equality strategy sessions of the technology deployment even with clear relevance with the strategy's goals.

“This disclosure show yet again that the pledges to combat discrimination the police has undertaken via the race action plan are not being translated into wider practice. Our reports have cautioned that innovative tools are being rolled out in a context where ethnic inequalities, weak scrutiny and poor data collection continue to exist.

“Any use of this technology must meet strict national standards, be independently scrutinised, and demonstrate it diminishes rather than compounds racial disparity.”

Official Statement

A government representative stated: “The Home Office takes the findings of the report seriously and we have implemented changes. A updated software has been externally evaluated and procured, which has no statistically significant bias. It will be trialled early next year and will be subject to further assessment.

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