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Law enforcement agencies across the UK effectively campaigned to use a face scanning system acknowledged as biased against females, young people, and members of ethnic minority groups, following complaints that a more accurate version generated fewer investigative leads.

The Technology in Practice

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

Admitted Bias

The Home Office conceded last week that the technology was biased. This acknowledgment followed a review by the government's National Physical Laboratory determined it incorrectly matched people of Black and Asian heritage and females at much greater frequency than Caucasian males. The ministry said it “took steps on the findings”.

“This raises the question of whether facial recognition only becomes effective if users accept biases in race and sex. Convenience is a weak argument for overriding basic freedoms.”

Known Issue

Official papers show that this bias has been recognized for more than a year. Furthermore, law enforcement lobbied to reverse an initial decision that was intended 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 had a higher probability to suggest false positives for photos of women, individuals of Black ethnicity, and those aged 40 and under.

A Reversed Decision

In response, the National Police Chiefs’ Council (NPCC) ordered that the accuracy setting required for possible hits be increased to a level where the disparity was greatly diminished.

However, this directive was overturned the next month following complaints from police that the adjusted system was producing a lower number of “investigative leads”. Internal records show the stricter setting reduced the proportion of searches that yielded possible identifications from 56% to a just under 15%.

Profound Inequalities

Although the Home Office and NPCC refused to say what threshold is now in operation, the recent independent review found the system could generate false positives for Black women almost 100 times more frequently than for white women at certain settings.

The Home Office stated on these findings: “The testing found that in a specific scenarios the algorithm is more likely to wrongly flag some population segments in its match reports.”

Balancing Utility and Fairness

Outlining the effect of the brief increase to the system's confidence threshold, the NPCC documents state: “This adjustment greatly lessens the effect of bias across legally safeguarded attributes of ethnicity, generation and gender but had a substantially detrimental effect on police efficiency”. The documents add that police units argued that “a previously useful tool now delivered outcomes of questionable value”.

Broader Rollout Plans

Meanwhile, the government has launched a ten-week consultation on its proposals to expand the use of facial recognition technology. 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 independent scrutiny and oversight board for the police race action plan, said: “There was very little consideration through race action plan meetings of the technology deployment despite clear relevance with the plan’s concerns.

“This disclosure demonstrate yet again that the pledges to combat discrimination the police has made through the race action plan are failing to be integrated into broader operations. Independent assessments have warned that new technologies are being rolled out in a landscape where ethnic inequalities, weak scrutiny and faulty information gathering continue to exist.

“All deployment of this technology must meet strict national standards, be subject to external review, and demonstrate it reduces rather than compounds ethnic bias.”

Home Office Response

A government representative stated: “We takes the findings of the report seriously and we have already taken action. A updated software has been independently tested and acquired, which has demonstrated no measurable discrimination. It will be trialled in the coming months and will be undergo evaluation.

“Our priority is ensuring public safety. This gamechanging technology will assist officers to put criminals and rapists behind bars. There is human involvement in every step of the procedure and no further action would be taken without specialist personnel meticulously examining the results.”