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Law enforcement agencies across the UK successfully lobbied to deploy a face scanning system acknowledged as biased against women, youths, and individuals from ethnic minority groups, following complaints that a less biased version generated fewer potential suspects.

The Technology in Practice

UK forces utilize the national police database to carry out searches using historical face recognition. This process entails matching a reference photograph of a person of interest against a repository of over 19 million custody photos to find potential matches.

Acknowledged Discrimination

The Home Office admitted last week that the system was biased. This acknowledgment followed a review by the National Physical Laboratory (NPL) found it misidentified Black and Asian people and women at significantly higher rates 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 tolerate biases in ethnicity and sex. Operational ease is a poor argument for overriding basic freedoms.”

Known Issue

Internal documents reveal that this bias has been known about for more than a year. Furthermore, law enforcement lobbied to reverse an initial decision that was designed to address the problem.

Senior officers were notified of the algorithmic discrimination in late 2024. The government-ordered NPL review concluded the system was more likely to produce incorrect matches for images depicting females, 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 significantly reduced.

However, this decision was overturned the next month following complaints from police that the adjusted system was generating a lower number of “useful lines of inquiry”. NPCC documents show the stricter setting cut the number of queries that yielded potential matches from 56% to a just 14%.

Profound Inequalities

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

The ministry stated 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.”

Balancing Utility and Fairness

Describing the effect of the brief increase to the system's accuracy setting, the NPCC documents state: “This adjustment significantly reduces the effect of bias across legally safeguarded attributes of race, age and sex but had a substantially detrimental effect on police efficiency”. The documents further note that forces complained that “a once effective tactic now delivered results of questionable value”.

Wider Implementation Proposals

Meanwhile, the UK administration has launched a two-and-a-half-month consultation on its proposals to widen the use of biometric scanning systems. The minister for police Sarah Jones has described the technology as the “most significant advance since genetic fingerprinting”.

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, commented: “There was scant discussion through race action plan meetings of the technology deployment despite clear relevance with the strategy's goals.

“These revelations show once again that the pledges to combat discrimination policing has made through the race action plan are not being translated into broader operations. Our reports have warned that innovative tools are being implemented in a landscape where ethnic inequalities, inadequate oversight and poor data collection continue to exist.

“Any use of facial recognition must meet rigorous official guidelines, be independently scrutinised, and demonstrate it reduces rather than exacerbates racial disparity.”

Home Office Response

A Home Office spokesperson said: “The Home Office takes the conclusions of the study seriously and we have already taken action. A new algorithm 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.

“The foremost aim is ensuring public safety. This gamechanging technology will assist officers to put criminals and rapists behind bars. There is human involvement in each stage of the procedure and no further action would be pursued without specialist personnel meticulously examining the output.”