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Law enforcement agencies across the United Kingdom successfully lobbied to deploy a facial recognition system known to be biased against females, young people, and members of minority ethnic backgrounds, after complaining that a less biased version produced a reduced number of potential suspects.

How the System Works

UK forces utilize the police national database (PND) to carry out retrospective facial recognition searches. This process involves matching a “probe image” of a person of interest against a database of more than 19 million custody photos to identify possible hits.

Admitted Bias

The UK interior ministry admitted last week that the technology was biased. This acknowledgment came after a review by the National Physical Laboratory (NPL) found it misidentified people of Black and Asian heritage and women at significantly higher rates than Caucasian males. The ministry stated it “had acted on the findings”.

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

Known Issue

Official papers reveal that this bias has been recognized for more than a year. Furthermore, law enforcement argued to overturn an earlier ruling that was designed to address the problem.

Senior officers were informed 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 images depicting females, Black people, and those under 40 years old.

A Policy U-Turn

In response, the National Police Chiefs’ Council (NPCC) ordered that the confidence threshold required for potential matches be raised to a level where the disparity was significantly reduced.

However, this decision was overturned the following month following complaints from police that the adjusted system was producing a lower number of “investigative leads”. NPCC documents show the higher threshold reduced the proportion of queries resulting in possible identifications from over half to a mere 14%.

Profound Inequalities

Although the Home Office and NPCC declined to specify what setting is currently used, the latest independent review found the system could generate incorrect matches for women of Black heritage almost 100 times more often than for white women at certain settings.

The Home Office commented on these results: “Our evaluation found that in a specific scenarios the software is has a greater tendency to incorrectly include some demographic groups in its match reports.”

Balancing Utility and Fairness

Describing the effect of the brief increase to the system's accuracy setting, the police records state: “The change significantly reduces the impact of discrimination across legally safeguarded attributes of ethnicity, generation and sex but had a substantially detrimental effect on operational effectiveness”. The papers add that forces argued that “a previously useful tool returned results of limited benefit”.

Wider Implementation Proposals

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

Expert and Oversight Concerns

The chair of a police oversight board, head of the advisory panel for the national policing equality strategy, said: “We observed very little discussion through equality strategy sessions of the facial recognition rollout even with clear relevance with the strategy's goals.

“These revelations demonstrate yet again that the pledges to combat discrimination policing has made through the equality initiative are failing to be integrated into wider practice. Independent assessments have cautioned that new technologies are being implemented in a landscape where ethnic inequalities, inadequate oversight and poor data collection already persist.

“Any use of this technology must meet rigorous official guidelines, be subject to external review, and demonstrate it diminishes rather than exacerbates racial disparity.”

Home Office Response

A government representative said: “The Home Office takes the conclusions of the study seriously and we have implemented changes. A updated software has been externally evaluated and acquired, which has no statistically significant bias. It will be tested in the coming months and will be subject to evaluation.

“The foremost aim is ensuring public safety. This revolutionary tool will assist officers to apprehend and prosecute offenders. There is human involvement in each stage of the process and no further action would be pursued without specialist personnel carefully reviewing the output.”