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Police forces across the UK successfully lobbied to use a facial recognition system known to be biased against females, young people, and members of minority ethnic backgrounds, following complaints that a less biased version produced fewer potential suspects.

The Technology in Practice

UK forces use the national police database to conduct searches using historical face recognition. This process entails matching a “probe image” of a person of interest against a database of more than 19 million mugshots to identify possible hits.

Acknowledged Discrimination

The UK interior ministry admitted last week that the technology was biased. This acknowledgment followed a review by the National Physical Laboratory (NPL) determined it misidentified people of Black and Asian heritage and females at much greater frequency than Caucasian males. The ministry stated it “had acted on the findings”.

“This raises the question of whether this technology only becomes useful if users accept biases in ethnicity and sex. Operational ease is a weak argument for disregarding basic freedoms.”

Long-Standing Problem

Official papers show 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 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 more likely to produce false positives for images depicting females, Black people, and those under 40 years old.

A Reversed Decision

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

However, this decision was overturned the following month after forces complained that the adjusted system was producing fewer “useful lines of inquiry”. NPCC documents show the higher threshold reduced the proportion of queries that yielded possible identifications from 56% to a mere under 15%.

Severe Disparities

Although the Home Office and NPCC declined to specify what setting is now in operation, the recent NPL study discovered the system could produce incorrect matches for women of Black heritage nearly a hundred times more often than for Caucasian women at certain settings.

The Home Office stated on these results: “Our evaluation identified that in a specific scenarios the software is has a greater tendency to wrongly flag some demographic groups in its search results.”

Operational Effectiveness vs. Bias

Outlining the impact of the brief increase to the system's accuracy setting, the police records note: “This adjustment greatly lessens the effect of bias across legally safeguarded attributes of ethnicity, generation and sex but had a substantially detrimental effect on police efficiency”. The papers further note that forces argued that “a previously useful tool now delivered results of questionable value”.

Wider Implementation Proposals

Meanwhile, the government has opened a two-and-a-half-month public review on its proposals to widen the use of facial recognition technology. Policing minister the relevant minister has described the technology as the “most significant advance since DNA matching”.

Criticism from Advisors and Monitors

Abimbola Johnson, head of the advisory panel for the national policing equality strategy, said: “There was very little consideration in race action plan meetings of the technology deployment even with clear relevance with the plan’s concerns.

“This disclosure show yet again that the anti-racism commitments policing has made via the equality initiative are not being translated into broader operations. Independent assessments have cautioned that innovative tools are being implemented in a landscape where racial disparities, weak scrutiny and faulty information gathering continue to exist.

“Any use of this technology must meet rigorous official guidelines, be subject to external review, and prove it reduces rather than exacerbates racial disparity.”

Official Statement

A Home Office spokesperson said: “The Home Office treat 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 tested in the coming months and will be subject to evaluation.

“Our priority is protecting the public. This revolutionary tool will assist officers to put criminals and rapists behind bars. There is human involvement in each stage of the process and no arrest or charge would be taken without trained officers meticulously examining the results.”