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Police forces across the United Kingdom effectively campaigned to deploy a facial recognition system known to be biased against females, young people, and individuals from minority ethnic backgrounds, following complaints that a less biased version generated a reduced number of potential suspects.

How the System Works

British police use the national police database to carry out retrospective facial recognition searches. This process involves matching a reference photograph of a person of interest against a repository of more than 19 million custody photos to find potential matches.

Admitted Bias

The UK interior ministry admitted last week that the system was flawed. This acknowledgment came after a review by the government's National Physical Laboratory determined it incorrectly matched people of Black and Asian heritage and women at significantly higher rates than white men. The ministry said it “took steps on the findings”.

“It prompts the issue of whether facial recognition only becomes effective if users tolerate discrimination in ethnicity and sex. Operational ease is a weak argument for overriding basic freedoms.”

Known Issue

Official papers reveal that this discriminatory flaw has been recognized for over twelve months. Furthermore, law enforcement lobbied to reverse an initial decision that was designed to mitigate the problem.

Senior officers were informed of the system's bias in late 2024. The Home Office-commissioned laboratory study found the system was had a higher probability to produce false positives for images depicting women, individuals of Black ethnicity, and those under 40 years old.

A Reversed Decision

In response, the national police leadership body mandated that the accuracy setting required for possible hits be raised to a level where the disparity was significantly reduced.

However, this decision was overturned the next month after forces complained that the modified technology was generating fewer “useful lines of inquiry”. NPCC documents show the stricter setting cut the proportion of queries that yielded possible identifications from over half to a just 14%.

Severe Disparities

Although the authorities declined to specify what setting is now in operation, the recent NPL study discovered the system could produce false positives for Black women nearly a hundred times more frequently than for Caucasian women at specific configurations.

The Home Office stated on these results: “Our evaluation identified that in a specific scenarios the algorithm is has a greater tendency to incorrectly include some population segments in its search results.”

Balancing Utility and Fairness

Describing the effect of the brief increase to the system's confidence threshold, the police records note: “This adjustment significantly reduces the impact of bias across protected characteristics of ethnicity, age and sex but had a significant negative impact on operational effectiveness”. The documents further note that forces complained that “a once effective tactic returned outcomes of limited benefit”.

Wider Implementation Proposals

Meanwhile, the government has launched a two-and-a-half-month consultation on its plans to widen the use of biometric scanning systems. Policing minister the relevant minister has described the tool as the “biggest breakthrough since DNA matching”.

Expert and Oversight Concerns

Abimbola Johnson, chair of the advisory panel for the national policing equality strategy, said: “There was scant discussion in race action plan meetings of the technology deployment despite obvious cross-over with the plan’s concerns.

“These revelations show once again that the pledges to combat discrimination the police has made through the equality initiative are failing to be integrated into broader operations. Independent assessments have cautioned that innovative tools are being implemented in a landscape where racial disparities, inadequate oversight and faulty information gathering already persist.

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

Home Office Response

A Home Office spokesperson stated: “We treat the findings of the study seriously and we have already taken action. A updated software has been externally evaluated and acquired, which has demonstrated no measurable discrimination. It will be tested in the coming months and will be subject to further assessment.

“The foremost aim is ensuring public safety. This gamechanging technology will assist police 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 trained officers meticulously examining the output.”