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Police forces across the UK effectively campaigned to use a facial recognition system known to be discriminatory against women, youths, and members of minority ethnic backgrounds, following complaints that a more accurate version generated a reduced number of potential suspects.

How the System Works

British police use the national police database to carry out searches using historical face recognition. This process involves matching a reference photograph of a person of interest against a repository of more than 19 million mugshots to identify potential matches.

Acknowledged Discrimination

The UK interior ministry admitted last week that the technology was flawed. This admission followed a review by the National Physical Laboratory (NPL) found it misidentified Black and Asian people and women at significantly higher rates than white men. The Home Office said it “took steps on the findings”.

“It prompts the issue of whether facial recognition only becomes effective if users accept biases in race and sex. Convenience is a weak argument for disregarding fundamental rights.”

Long-Standing Problem

Internal documents reveal that this bias has been known about for more than a year. Furthermore, law enforcement lobbied to reverse an earlier ruling that was intended to address the problem.

Police bosses were informed of the algorithmic discrimination in late 2024. The government-ordered laboratory study concluded the system was had a higher probability to produce false positives for photos of women, individuals of Black ethnicity, and those under 40 years old.

A Reversed Decision

In reaction, the National Police Chiefs’ Council (NPCC) mandated that the confidence threshold required for potential matches be raised to a point where the bias was significantly reduced.

However, this decision was reversed the next month following complaints from police that the adjusted system was generating a lower number of “investigative leads”. Internal records show the higher threshold reduced the proportion of searches resulting in possible identifications from over half to a just under 15%.

Severe Disparities

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

The Home Office commented on these results: “The testing identified that in a specific scenarios the software is more likely to wrongly flag some population segments in its search results.”

Operational Effectiveness vs. Bias

Describing the effect of the brief increase to the system's confidence threshold, the NPCC documents note: “The change significantly reduces the effect of discrimination across protected characteristics of ethnicity, age and sex but had a substantially detrimental effect on operational effectiveness”. The papers add that forces argued that “a once effective tactic returned results of questionable value”.

Broader Rollout Plans

Meanwhile, the government has opened a ten-week consultation on its plans to widen the use of facial recognition technology. The minister for police Sarah Jones has labeled the technology as the “biggest breakthrough since DNA matching”.

Expert and Oversight Concerns

Abimbola Johnson, chair of the advisory panel for the police race action plan, commented: “There was very little consideration in equality strategy sessions of the facial recognition rollout even with clear relevance with the plan’s concerns.

“This disclosure demonstrate yet again that the anti-racism commitments policing has undertaken through the race action plan are failing to be integrated into wider practice. Our reports have warned that new technologies are being rolled out in a context where racial disparities, inadequate oversight and poor data collection already persist.

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

Home Office Response

A government representative stated: “We takes the findings of the study seriously and we have implemented changes. A new algorithm has been externally evaluated and acquired, which has demonstrated no measurable discrimination. It will be trialled early next year and will be undergo further assessment.

“The foremost aim is protecting the public. This gamechanging technology will assist officers to apprehend and prosecute offenders. There is human involvement in every step of the procedure and no further action would be pursued without specialist personnel meticulously examining the output.”