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Law enforcement agencies across the United Kingdom effectively campaigned to deploy a face scanning system acknowledged as biased against women, youths, and members of ethnic minority groups, following complaints that a less biased version produced fewer potential suspects.

How the System Works

British police utilize the police national database (PND) to conduct searches using historical face recognition. This process 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 conceded last week that the system was biased. This acknowledgment came after a review by the government's National Physical Laboratory determined it incorrectly matched Black and Asian people and women at significantly higher rates than white men. The Home Office stated it “took steps on the findings”.

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

Known Issue

Internal documents reveal that this bias has been known about for over twelve months. Furthermore, law enforcement lobbied to reverse an initial decision that was intended to mitigate the problem.

Police bosses were notified of the algorithmic discrimination in September 2024. The government-ordered laboratory study found the system was more likely to produce false positives 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 confidence threshold required for potential matches be raised to a level where the bias was greatly diminished.

However, this decision was overturned the next month after forces complained that the adjusted system was generating a lower number of “investigative leads”. NPCC documents indicate the stricter setting cut the proportion of queries that yielded potential matches from 56% to a just 14%.

Severe Disparities

Although the authorities declined to specify what setting is currently used, the latest independent review discovered the system could produce incorrect matches for Black women nearly a hundred times more often than for Caucasian women at certain settings.

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

Balancing Utility and Fairness

Outlining the effect of the temporary raise to the system's accuracy setting, the police records note: “The change greatly lessens the impact of bias across protected characteristics of ethnicity, age and gender but had a substantially detrimental effect on police efficiency”. The papers add that police units complained that “a once effective tactic returned results of limited benefit”.

Broader Rollout Plans

Meanwhile, the UK administration has launched a two-and-a-half-month consultation on its proposals to widen the use of facial recognition technology. The minister for police the relevant minister has labeled the technology as the “most significant advance since DNA matching”.

Expert and Oversight Concerns

Abimbola Johnson, chair of the advisory panel for the police race action plan, commented: “There was scant discussion in race action plan meetings of the technology deployment despite obvious cross-over with the strategy's goals.

“These revelations show yet again that the pledges to combat discrimination the police has made through the race action plan are failing to be integrated into broader operations. Independent assessments have cautioned that new technologies are being rolled out in a landscape where ethnic inequalities, inadequate oversight and faulty information gathering already persist.

“Any use of this technology must meet rigorous official guidelines, be independently scrutinised, and demonstrate it diminishes rather than exacerbates ethnic bias.”

Home Office Response

A government representative said: “The Home Office treat the conclusions of the report with utmost gravity and we have implemented changes. A updated software has been externally evaluated and procured, which has no statistically significant bias. 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 police to apprehend and prosecute offenders. There is officer review in each stage of the procedure and no further action would be taken without trained officers carefully reviewing the output.”