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Law enforcement agencies across the UK successfully lobbied to use a face scanning system acknowledged as discriminatory against females, youths, and members of minority ethnic backgrounds, after complaining that a less biased version generated a reduced number of investigative leads.

How the System Works

British police use the national police database to conduct retrospective facial recognition searches. This process involves matching a “probe image” of a suspect against a repository of more than 19 million mugshots to find potential matches.

Acknowledged Discrimination

The Home Office admitted last week that the system was biased. This acknowledgment followed a review by the government's National Physical Laboratory found it incorrectly matched Black and Asian people and women at much greater frequency than Caucasian males. The Home Office stated it “took steps on the findings”.

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

Long-Standing Problem

Official papers show that this bias has been known about for more than a year. Furthermore, law enforcement lobbied to reverse an initial decision that was designed to address the problem.

Senior officers were notified of the algorithmic discrimination in September 2024. The Home Office-commissioned NPL review found the system was more likely to produce 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 Chiefs’ Council (NPCC) ordered that the confidence threshold required for possible hits be raised to a point where the disparity was greatly diminished.

However, this decision was reversed the following month after forces complained that the adjusted system was producing a lower number of “useful lines of inquiry”. Internal records indicate the higher threshold reduced the number of searches resulting in possible identifications from over half to a mere under 15%.

Severe Disparities

Although the authorities declined to specify what threshold is currently used, the recent independent review discovered the system could generate incorrect matches for women of Black heritage almost 100 times more frequently than for Caucasian women at certain settings.

The Home Office commented on these findings: “Our evaluation found that in a specific scenarios the algorithm is more likely to wrongly flag some demographic groups in its match reports.”

Operational Effectiveness vs. Bias

Describing the effect of the temporary raise to the system's confidence threshold, the police records state: “This adjustment greatly lessens the impact of discrimination across protected characteristics of ethnicity, generation and sex but had a substantially detrimental effect on police efficiency”. The documents add that police units argued that “a previously useful tool returned results of limited benefit”.

Broader Rollout Plans

Meanwhile, the government has launched a two-and-a-half-month consultation on its plans to widen the use of biometric scanning systems. The minister for police the relevant minister has labeled the tool as the “biggest breakthrough since genetic fingerprinting”.

Expert and Oversight Concerns

Abimbola Johnson, head of the independent scrutiny and oversight board for the national policing equality strategy, said: “We observed very little consideration through race action plan meetings of the technology deployment even with clear relevance with the plan’s concerns.

“This disclosure demonstrate yet again that the pledges to combat discrimination policing has undertaken through the race action plan are failing to be integrated into broader operations. Our reports have cautioned that innovative tools are being implemented in a landscape where racial disparities, inadequate oversight and poor data collection continue to exist.

“All deployment of this technology must meet rigorous official guidelines, be independently scrutinised, and demonstrate it diminishes rather than exacerbates racial disparity.”

Home Office Response

A government representative stated: “We takes the conclusions of the study with utmost gravity and we have already taken action. A updated software has been externally evaluated and acquired, which has demonstrated no measurable discrimination. It will be trialled early next year and will be undergo evaluation.

“The foremost aim is ensuring public safety. This gamechanging technology will assist officers to put criminals and rapists behind bars. There is officer review in each stage of the process and no arrest or charge would be taken without trained officers carefully reviewing the results.”