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Police forces across the United Kingdom effectively campaigned to use a facial recognition system known to be biased against females, youths, and individuals from minority ethnic backgrounds, following complaints that a more accurate version generated fewer investigative leads.

The Technology in Practice

British police use the national police database to conduct searches using historical face recognition. This process entails comparing a reference photograph of a person of interest against a database of more than 19 million custody photos to find potential matches.

Admitted Bias

The Home Office conceded last week that the technology was biased. This acknowledgment came after a review by the government's National Physical Laboratory determined it misidentified people of Black and Asian heritage and females at much greater frequency than Caucasian males. The ministry stated it “took steps on the findings”.

“It prompts the issue of whether this technology only becomes useful if users tolerate biases in ethnicity and sex. Operational ease is a weak argument for disregarding basic freedoms.”

Long-Standing Problem

Internal documents show that this bias has been recognized for more than a year. Furthermore, police forces lobbied to reverse an earlier ruling that was designed to address the problem.

Senior officers were notified of the system's bias in late 2024. The government-ordered NPL review concluded the system was had a higher probability to suggest false positives for photos of women, individuals of Black ethnicity, 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 possible hits be increased to a point where the disparity was greatly diminished.

However, this directive was overturned the next month following complaints from police that the adjusted system was generating fewer “investigative leads”. Internal records show the stricter setting cut the number of searches resulting in potential matches from 56% to a mere under 15%.

Profound Inequalities

Although the authorities refused to say what threshold is currently used, the recent independent review discovered the system could produce false positives for Black women nearly a hundred times more often than for Caucasian women at specific configurations.

The Home Office commented on these findings: “The testing found that in a specific scenarios the software is has a greater tendency to wrongly flag some population segments in its match reports.”

Balancing Utility and Fairness

Describing the impact of the brief increase to the system's confidence threshold, the NPCC documents note: “The change significantly reduces the effect of bias across protected characteristics of ethnicity, age and sex but had a significant negative impact on police efficiency”. The papers further note that forces argued that “a previously useful tool returned outcomes of limited benefit”.

Wider Implementation Proposals

Meanwhile, the government has launched a two-and-a-half-month public review on its plans to widen 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, commented: “There was very little discussion through equality strategy sessions of the facial recognition rollout even with obvious cross-over with the plan’s concerns.

“This disclosure show once again that the anti-racism commitments the police has undertaken through the equality initiative are failing to be integrated into wider practice. Independent assessments have warned that new technologies are being rolled out in a context where ethnic inequalities, inadequate oversight and poor data collection continue to exist.

“Any use of this technology must meet rigorous official guidelines, be independently scrutinised, and prove it diminishes rather than exacerbates racial disparity.”

Home Office Response

A Home Office spokesperson said: “We treat the findings of the study with utmost gravity 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 ensuring public safety. This revolutionary tool will support police to put criminals and rapists behind bars. There is officer review in every step of the procedure and no further action would be taken without trained officers meticulously examining the results.”