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Law enforcement agencies across the United Kingdom effectively campaigned to use a facial recognition system known to be biased against females, youths, and members of minority ethnic backgrounds, after complaining that a more accurate version generated a reduced number of potential suspects.

How the System Works

British police utilize the national police database to carry out searches using historical face recognition. This procedure involves matching a “probe image” of a person of interest against a database of over 19 million mugshots to identify potential matches.

Acknowledged Discrimination

The Home Office admitted last week that the system was flawed. This admission followed a study by the government's National Physical Laboratory found it incorrectly matched Black and Asian people and females at significantly higher rates than Caucasian males. The ministry said 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 weak argument for disregarding fundamental rights.”

Known Issue

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

Senior officers were informed of the algorithmic discrimination in late 2024. The Home Office-commissioned laboratory study found the system was more likely to suggest false positives for images depicting women, individuals of Black ethnicity, and those under 40 years old.

A Reversed Decision

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

However, this decision was overturned the following month after forces complained that the adjusted system was producing fewer “useful lines of inquiry”. Internal records indicate the higher threshold reduced the number of searches that yielded potential matches from over half to a just 14%.

Severe Disparities

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

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

Operational Effectiveness vs. Bias

Describing the effect of the brief increase to the system's confidence threshold, the NPCC documents state: “The change significantly reduces the effect of discrimination across legally safeguarded attributes of race, generation and sex but had a substantially detrimental effect on police efficiency”. 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 two-and-a-half-month public review on its plans to widen the use of biometric scanning systems. The minister for police the relevant minister has described the tool as the “most significant advance since DNA matching”.

Criticism from Advisors and Monitors

The chair of a police oversight board, head of the advisory panel for the police race action plan, commented: “There was very little discussion through race action plan meetings of the technology deployment even with obvious cross-over with the plan’s concerns.

“This disclosure show yet again that the pledges to combat discrimination the police has made through the equality initiative are failing to be integrated into broader operations. Our reports have cautioned that innovative tools are being rolled out in a landscape where ethnic inequalities, weak scrutiny and poor data collection already persist.

“All deployment of facial recognition must meet rigorous official guidelines, be independently scrutinised, and demonstrate it reduces rather than exacerbates ethnic bias.”

Official Statement

A Home Office spokesperson said: “The Home Office treat the findings of the study with utmost gravity and we have implemented changes. A new algorithm has been independently tested and procured, which has demonstrated no measurable discrimination. It will be tested in the coming months and will be subject to evaluation.

“Our priority is protecting the public. This gamechanging technology will support police to apprehend and prosecute offenders. There is officer review in every step of the process and no further action would be taken without trained officers carefully reviewing the output.”