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Law enforcement agencies across the UK successfully lobbied to use a face scanning system known to be biased against women, youths, and members of ethnic minority groups, following complaints that a more accurate version produced fewer investigative leads.

The Technology in Practice

British police use the national police database to carry out searches using historical face recognition. This process involves comparing a “probe image” of a suspect against a repository of more than 19 million custody photos to find potential matches.

Admitted Bias

The UK interior ministry conceded last week that the system was biased. This admission followed a review by the National Physical Laboratory (NPL) found it misidentified Black and Asian people and women at much greater frequency than white men. The Home Office stated it “took steps on the findings”.

“It prompts the issue of whether this technology only becomes effective if users accept discrimination in race and gender. Operational ease is a weak argument for disregarding fundamental rights.”

Known Issue

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

Police bosses were informed of the algorithmic discrimination in late 2024. The Home Office-commissioned NPL review concluded the system was had a higher probability to suggest incorrect matches for photos of females, Black people, and those under 40 years old.

A Reversed Decision

In reaction, the national police leadership body mandated that the accuracy setting required for potential matches be raised to a level where the disparity was greatly diminished.

However, this decision was reversed the next month following complaints from police that the modified technology was generating a lower number of “useful lines of inquiry”. Internal records indicate the higher threshold cut the proportion of searches resulting in potential matches from 56% to a just 14%.

Severe Disparities

Although the Home Office and NPCC refused to say what threshold is now in operation, the latest independent review discovered the system could produce incorrect matches for women of Black heritage almost 100 times more frequently than for white women at specific configurations.

The Home Office commented on these findings: “The testing found that in a limited set of circumstances the software is has a greater tendency to incorrectly include some population segments in its search results.”

Operational Effectiveness vs. Bias

Describing the impact of the brief increase to the system's accuracy setting, the police records note: “The change greatly lessens the effect of discrimination across protected characteristics of race, age and sex but had a significant negative impact on operational effectiveness”. The documents add that police units complained that “a previously useful tool returned outcomes of questionable value”.

Broader Rollout Plans

Meanwhile, the government has launched a two-and-a-half-month public review on its plans to expand the use of biometric scanning systems. The minister for police the relevant minister has described the tool as the “most significant advance since DNA matching”.

Expert and Oversight Concerns

The chair of a police oversight board, chair of the advisory panel for the national policing equality strategy, commented: “There was very little discussion in race action plan meetings of the technology deployment despite clear relevance with the plan’s concerns.

“These revelations demonstrate yet again that the pledges to combat discrimination the police has made through the equality initiative are not being translated into broader operations. Our reports have warned that innovative tools are being implemented in a context where ethnic inequalities, weak scrutiny and faulty information gathering continue to exist.

“All deployment of facial recognition must meet rigorous official guidelines, be independently scrutinised, and prove it reduces rather than compounds ethnic bias.”

Official Statement

A Home Office spokesperson said: “We takes 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 trialled in the coming months and will be subject to further assessment.

“Our priority is protecting the public. This gamechanging technology will support officers to apprehend and prosecute offenders. There is human involvement in every step of the process and no further action would be taken without trained officers carefully reviewing the results.”