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Police forces across the United Kingdom successfully lobbied to use a facial recognition system known to be biased against women, youths, and individuals from minority ethnic backgrounds, after complaining that a more accurate version produced a reduced number of potential suspects.

How the System Works

UK forces use the national police database to conduct searches using historical face recognition. This process entails matching a reference photograph of a person of interest against a database of more than 19 million mugshots to identify possible hits.

Acknowledged Discrimination

The UK interior ministry admitted last week that the technology was flawed. This acknowledgment came after a study by the government's National Physical Laboratory found it incorrectly matched people of Black and Asian heritage and females at significantly higher rates than white men. The ministry stated it “took steps on the findings”.

“This raises the issue of whether this technology only becomes effective if users accept discrimination in race and sex. Convenience is a poor argument for disregarding fundamental rights.”

Known Issue

Internal documents show that this discriminatory flaw has been known about for over twelve months. Furthermore, police forces argued to overturn an initial decision that was intended to address the problem.

Senior officers were notified of the system's bias in late 2024. The Home Office-commissioned laboratory study found the system was more likely to produce false positives for images depicting women, Black people, and those under 40 years old.

A Policy U-Turn

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

However, this decision was overturned the next month following complaints from police that the adjusted system was producing fewer “investigative leads”. NPCC documents indicate the higher threshold reduced the proportion of searches resulting in potential matches from 56% to a just under 15%.

Severe Disparities

Although the authorities refused to say what setting is currently used, the recent independent review discovered the system could generate false positives for women of Black heritage nearly a hundred times more often than for white women at certain settings.

The ministry stated on these results: “The testing found that in a specific scenarios the software is has a greater tendency to wrongly flag some demographic groups in its search results.”

Balancing Utility and Fairness

Describing the impact of the temporary raise to the system's confidence threshold, the NPCC documents note: “This adjustment greatly lessens the impact of discrimination across legally safeguarded attributes of race, age and sex but had a significant negative impact on operational effectiveness”. The papers further note that forces complained that “a once effective tactic returned results of limited benefit”.

Broader Rollout Plans

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

Expert and Oversight Concerns

The chair of a police oversight board, head of the independent scrutiny and oversight board for the national policing equality strategy, said: “There was very little discussion through equality strategy sessions of the facial recognition rollout even with clear relevance with the plan’s concerns.

“This disclosure show yet again that the anti-racism commitments the police has undertaken through the equality initiative are not being translated into broader operations. Independent assessments have warned that innovative tools are being implemented in a context where ethnic inequalities, inadequate oversight and poor data collection continue to exist.

“Any use of this technology must adhere to strict national standards, be subject to external review, and demonstrate it reduces rather than exacerbates ethnic bias.”

Home Office Response

A Home Office spokesperson said: “The Home Office treat the conclusions 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 tested early next year and will be undergo evaluation.

“The foremost aim is ensuring public safety. This revolutionary tool will assist officers to apprehend and prosecute offenders. There is officer review in every step of the process and no arrest or charge would be taken without trained officers carefully reviewing the output.”