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Law enforcement agencies across the UK effectively campaigned to use a facial recognition system acknowledged as biased against females, youths, and individuals from ethnic minority groups, following complaints that a more accurate version produced fewer investigative leads.

The Technology in Practice

British police use the police national database (PND) to carry out searches using historical face recognition. This process involves matching a “probe image” of a suspect against a repository of more than 19 million custody photos to identify possible hits.

Acknowledged Discrimination

The UK interior ministry admitted last week that the system was biased. This admission came after a study by the National Physical Laboratory (NPL) found it misidentified people of Black and Asian heritage and females at significantly higher rates than white men. The Home Office stated it “took steps on the findings”.

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

Known Issue

Internal documents show that this bias has been recognized for over twelve months. Furthermore, law enforcement lobbied to reverse an initial decision that was designed to address the problem.

Senior officers were informed of the system's bias in late 2024. The Home Office-commissioned NPL review found the system was had a higher probability to suggest incorrect matches for photos of females, Black people, and those under 40 years old.

A Policy U-Turn

In reaction, the National Police Chiefs’ Council (NPCC) mandated that the accuracy setting required for possible hits be increased to a level where the disparity was greatly diminished.

However, this decision was overturned the next month following complaints from police that the modified technology was producing fewer “investigative leads”. NPCC documents show the stricter setting cut the proportion of queries resulting in possible identifications from 56% to a mere 14%.

Profound Inequalities

Although the authorities declined to specify what threshold is now in operation, the latest NPL study discovered the system could produce incorrect matches for women of Black heritage nearly a hundred times more frequently than for Caucasian women at certain settings.

The ministry stated on these results: “The testing found that in a limited set of circumstances the algorithm is has a greater tendency to incorrectly include some demographic groups in its search results.”

Operational Effectiveness vs. Bias

Describing the impact of the temporary raise to the system's confidence threshold, the NPCC documents note: “The change 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 argued that “a previously useful tool now delivered results of limited benefit”.

Wider Implementation Proposals

Meanwhile, the government has opened a two-and-a-half-month public review on its plans to expand the use of facial recognition technology. Policing minister Sarah Jones has described the technology as the “biggest breakthrough since DNA matching”.

Criticism from Advisors and Monitors

The chair of a police oversight board, chair of the independent scrutiny and oversight board for the national policing equality strategy, commented: “We observed scant discussion through equality strategy sessions of the technology deployment even with clear relevance with the strategy's goals.

“This disclosure show once again that the anti-racism commitments the police has made via the equality initiative are failing to be integrated into wider practice. Independent assessments have cautioned that new technologies are being rolled out in a landscape where racial disparities, weak scrutiny and poor data collection continue to exist.

“All deployment of facial recognition must meet rigorous official guidelines, be subject to external review, and prove it reduces rather than exacerbates ethnic bias.”

Home Office Response

A government representative said: “The Home Office takes the findings of the report 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.

“The foremost aim is ensuring public safety. This revolutionary tool will assist police to apprehend and prosecute offenders. There is human involvement in every step of the procedure and no further action would be pursued without trained officers meticulously examining the output.”