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Police forces across the United Kingdom successfully lobbied to deploy a facial recognition system known to be discriminatory against females, young people, and members of minority ethnic backgrounds, following complaints that a more accurate version produced a reduced number of potential suspects.

How the System Works

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

Acknowledged Discrimination

The Home Office conceded last week that the system was biased. This acknowledgment came after a study by the government's National Physical Laboratory determined it misidentified people of Black and Asian heritage and women at much greater frequency than Caucasian males. The Home Office stated it “took steps on the findings”.

“It prompts the question of whether this technology only becomes effective if users accept biases in ethnicity and gender. Operational ease is a poor argument for disregarding fundamental rights.”

Known Issue

Internal documents show that this bias has been recognized for more than a year. Furthermore, police forces argued to overturn an earlier ruling that was intended to mitigate the problem.

Police bosses were notified of the algorithmic discrimination in September 2024. The government-ordered NPL review concluded the system was had a higher probability to suggest incorrect matches for photos of females, individuals of Black ethnicity, and those aged 40 and under.

A Reversed Decision

In reaction, the national police leadership body ordered that the confidence threshold required for potential matches be increased to a level where the disparity was greatly diminished.

However, this decision was reversed the next month after forces complained that the adjusted system was generating a lower number of “investigative leads”. NPCC documents show the higher threshold reduced the proportion of searches that yielded possible identifications from over half to a mere under 15%.

Severe Disparities

Although the authorities refused to say what threshold is now in operation, the recent independent review found the system could produce incorrect matches for women of Black heritage nearly a hundred times more often than for Caucasian women at specific configurations.

The Home Office stated on these results: “The testing found that in a limited set of circumstances the algorithm is has a greater tendency to wrongly flag some population segments in its match reports.”

Balancing Utility and Fairness

Outlining the impact of the temporary raise to the system's confidence threshold, the NPCC documents state: “This adjustment greatly lessens the impact of bias across protected characteristics of race, generation and sex but had a substantially detrimental effect on police efficiency”. The documents add that forces argued that “a previously useful tool now delivered outcomes of limited benefit”.

Wider Implementation Proposals

Meanwhile, the UK administration has opened a two-and-a-half-month consultation on its plans to expand the use of biometric scanning systems. The minister for police the relevant minister has labeled the tool as the “most significant advance since genetic fingerprinting”.

Expert and Oversight Concerns

Abimbola Johnson, head of the independent scrutiny and oversight board for the police race action plan, commented: “There was scant consideration through equality strategy sessions of the facial recognition rollout despite obvious cross-over with the plan’s concerns.

“These revelations demonstrate once again that the pledges to combat discrimination the police has made via the equality initiative are failing to be integrated into broader operations. Our reports have warned that innovative tools are being rolled out in a landscape where ethnic inequalities, weak scrutiny and faulty information gathering continue to exist.

“All deployment of facial recognition must adhere to rigorous official guidelines, be independently scrutinised, and demonstrate it diminishes rather than compounds racial disparity.”

Official Statement

A Home Office spokesperson said: “We takes the findings 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 early next year and will be subject to evaluation.

“The foremost aim is ensuring public safety. This revolutionary tool will support police to put criminals and rapists behind bars. There is officer review in each stage of the process and no arrest or charge would be pursued without trained officers carefully reviewing the output.”