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Police forces across the UK successfully lobbied to deploy a facial recognition system acknowledged as biased against women, youths, and individuals from ethnic minority groups, following complaints that a less biased version produced a reduced number of investigative leads.

The Technology in Practice

British police use the police national database (PND) to conduct 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 mugshots to identify possible hits.

Admitted Bias

The Home Office admitted last week that the system was biased. This admission came after a review by the National Physical Laboratory (NPL) determined it misidentified people of Black and Asian heritage and females at significantly higher rates than Caucasian males. The Home Office stated it “had acted on the findings”.

“It prompts the question of whether this technology only becomes effective if users accept discrimination in race and sex. Operational ease is a poor argument for overriding fundamental rights.”

Known Issue

Internal documents reveal that this bias has been known about for over twelve months. Furthermore, law enforcement argued to overturn an earlier ruling that was designed to mitigate the problem.

Police bosses were notified of the algorithmic discrimination in late 2024. The Home Office-commissioned laboratory study found the system was more likely to suggest false positives for photos of women, 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 overturned the next month following complaints from police that the adjusted system was producing a lower number of “investigative leads”. NPCC documents indicate the higher threshold cut the number of queries resulting in possible identifications from over half to a just 14%.

Profound Inequalities

Although the authorities refused to say what threshold is now in operation, the latest independent review discovered the system could generate false positives for women of Black heritage nearly a hundred times more often than for Caucasian women at certain settings.

The Home Office commented on these findings: “Our evaluation identified that in a limited set of circumstances the software is has a greater tendency to incorrectly include some demographic groups in its match reports.”

Balancing Utility and Fairness

Outlining the impact of the temporary raise to the system's accuracy setting, the police records note: “The change significantly reduces the impact of bias across protected characteristics of ethnicity, age and gender but had a substantially detrimental effect on operational effectiveness”. The papers further note that forces complained that “a previously useful tool returned outcomes of questionable value”.

Wider Implementation Proposals

Meanwhile, the government has opened a ten-week consultation on its plans to expand the use of facial recognition technology. Policing minister the relevant minister has labeled the tool as the “most significant advance since genetic fingerprinting”.

Criticism from Advisors and Monitors

The chair of a police oversight board, chair of the independent scrutiny and oversight board for the police race action plan, said: “There was scant consideration through equality strategy sessions of the technology deployment despite clear relevance with the strategy's goals.

“This disclosure show once again that the anti-racism commitments policing has undertaken via the equality initiative are failing to be integrated into wider practice. Independent assessments have warned that innovative tools are being rolled out in a context where racial disparities, inadequate oversight and faulty information gathering already persist.

“Any use of this technology must meet strict national standards, be independently scrutinised, and demonstrate it diminishes rather than compounds ethnic bias.”

Home Office Response

A government representative said: “We treat the conclusions of the study with utmost gravity and we have already taken action. A new algorithm has been independently tested and procured, which has no statistically significant bias. It will be trialled in the coming months and will be subject to evaluation.

“The foremost aim is protecting the public. This gamechanging technology will support police to put criminals and rapists behind bars. There is human involvement in each stage of the procedure and no further action would be pursued without specialist personnel meticulously examining the results.”