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Police forces across the UK effectively campaigned to deploy a face scanning system acknowledged as discriminatory against women, young people, and individuals from minority ethnic backgrounds, after complaining that a less biased version generated a reduced number of potential suspects.

The Technology in Practice

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

Admitted Bias

The UK interior ministry admitted last week that the technology was flawed. This admission came after a review by the National Physical Laboratory (NPL) found it misidentified people of Black and Asian heritage and females at much greater frequency than Caucasian males. The ministry stated it “had acted on the findings”.

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

Known Issue

Internal documents reveal that this discriminatory flaw has been recognized for over twelve months. Furthermore, law enforcement lobbied to reverse an initial decision that was designed to address the problem.

Senior officers were informed of the algorithmic discrimination in September 2024. The government-ordered NPL review found the system was more likely to suggest false positives for images depicting women, individuals of Black ethnicity, and those aged 40 and under.

A Policy U-Turn

In reaction, the national police leadership body ordered that the accuracy setting required for potential matches be increased to a point where the disparity was significantly reduced.

However, this decision was overturned the following month after forces complained that the adjusted system was generating fewer “useful lines of inquiry”. NPCC documents show the higher threshold reduced the proportion of searches that yielded possible identifications from 56% to a just under 15%.

Severe Disparities

Although the Home Office and NPCC declined to specify what threshold is currently used, the latest independent review discovered the system could produce incorrect matches for women of Black heritage nearly a hundred times more frequently than for Caucasian women at certain settings.

The Home Office commented on these results: “The testing found that in a limited set of circumstances the software is more likely to incorrectly include some demographic groups 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: “This adjustment significantly reduces the impact of discrimination across legally safeguarded attributes of ethnicity, generation and sex but had a significant negative impact on operational effectiveness”. The documents further note that forces complained that “a previously useful tool returned results of questionable value”.

Wider Implementation Proposals

Meanwhile, the government has launched a two-and-a-half-month consultation on its proposals to widen the use of biometric scanning systems. Policing minister the relevant minister has described the tool as the “biggest breakthrough since DNA matching”.

Criticism from Advisors and Monitors

Abimbola Johnson, head of the advisory panel for the police race action plan, said: “There was very little discussion in equality strategy sessions of the facial recognition rollout despite clear relevance with the strategy's goals.

“This disclosure show once again that the anti-racism commitments policing has undertaken through the race action plan are not being translated into broader operations. Our reports have warned that new technologies are being implemented in a context where racial disparities, weak scrutiny and poor data collection already persist.

“Any use of this technology must meet strict national standards, be independently scrutinised, and demonstrate it diminishes rather than compounds racial disparity.”

Home Office Response

A Home Office spokesperson stated: “The Home Office takes the findings of the study with utmost gravity and we have already taken action. A new algorithm has been externally evaluated and procured, which has demonstrated no measurable discrimination. It will be trialled in the coming months and will be undergo evaluation.

“Our priority is ensuring public safety. This revolutionary tool will support officers to put criminals and rapists behind bars. There is human involvement in every step of the procedure and no further action would be taken without specialist personnel meticulously examining the output.”