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Law enforcement agencies across the United Kingdom successfully lobbied to use a face scanning system acknowledged as discriminatory against women, young people, and individuals from minority ethnic backgrounds, following complaints that a more accurate version generated a reduced number of potential suspects.

The Technology in Practice

UK forces utilize the police national database (PND) to conduct searches using historical face recognition. This procedure entails matching a reference photograph of a person of interest against a repository of more than 19 million custody photos to identify potential matches.

Admitted Bias

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

“It prompts the question of whether this technology only becomes effective if users tolerate discrimination in race and sex. Operational ease is a poor argument for disregarding basic freedoms.”

Known Issue

Official papers reveal that this discriminatory flaw has been recognized for over twelve months. Furthermore, police forces argued to overturn an earlier ruling that was designed to address the problem.

Police bosses were notified of the system's bias in late 2024. The government-ordered NPL review found the system was had a higher probability to suggest false positives for images depicting women, individuals of Black ethnicity, and those aged 40 and under.

A Policy U-Turn

In response, the national police leadership body ordered that the accuracy setting required for possible hits be increased to a level where the bias was greatly diminished.

However, this decision was overturned the next month after forces complained that the modified technology was producing fewer “investigative leads”. Internal records indicate the higher threshold reduced the proportion of queries that yielded possible identifications from 56% to a mere under 15%.

Severe Disparities

Although the authorities declined to specify what threshold is currently used, the recent NPL study discovered the system could produce incorrect matches for Black women almost 100 times more often than for white women at specific configurations.

The ministry commented on these results: “Our evaluation found that in a limited set of circumstances the software is has a greater tendency to wrongly flag some population segments in its search results.”

Balancing Utility and Fairness

Describing the effect of the temporary raise to the system's confidence threshold, the police records note: “This adjustment significantly reduces the effect of discrimination across legally safeguarded attributes of ethnicity, age and sex but had a significant negative impact on operational effectiveness”. The documents further note that forces argued that “a once effective tactic returned results of questionable value”.

Wider Implementation Proposals

Meanwhile, the UK administration has opened a two-and-a-half-month public review on its proposals to expand the use of biometric scanning systems. The minister for police the relevant minister has described the technology as the “biggest breakthrough since genetic fingerprinting”.

Criticism from Advisors and Monitors

The chair of a police oversight board, head of the independent scrutiny and oversight board for the national policing equality strategy, commented: “We observed very little discussion through equality strategy sessions of the facial recognition rollout despite obvious cross-over with the plan’s concerns.

“This disclosure demonstrate yet again that the anti-racism commitments policing has made through the race action plan are failing to be integrated into broader operations. Independent assessments have cautioned that innovative tools are being implemented in a context where ethnic inequalities, inadequate oversight and poor data collection already persist.

“All deployment of facial recognition must meet strict national standards, be independently scrutinised, and prove it reduces rather than exacerbates ethnic bias.”

Official Statement

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

“The foremost aim is ensuring public safety. This gamechanging technology will assist police to apprehend and prosecute offenders. There is officer review in each stage of the process and no arrest or charge would be pursued without trained officers meticulously examining the results.”