🔗 Share this article

Police forces across the UK effectively campaigned to use a facial recognition system known to be discriminatory against females, young people, and individuals from ethnic minority groups, after complaining that a less biased version produced fewer potential suspects.

How the System Works

UK forces use the police national database (PND) to carry out searches using historical face recognition. This procedure involves comparing a reference photograph of a suspect against a database of more than 19 million mugshots to find potential matches.

Acknowledged Discrimination

The Home Office conceded last week that the technology was flawed. This admission followed a review by the National Physical Laboratory (NPL) determined it misidentified Black and Asian people and females at much greater frequency than Caucasian males. The ministry said it “took steps on the findings”.

“This raises the question of whether this technology only becomes useful if users tolerate discrimination in race and gender. Convenience is a weak argument for overriding fundamental rights.”

Long-Standing Problem

Internal documents reveal that this discriminatory flaw has been recognized for more than a year. Furthermore, police forces argued to overturn an earlier ruling that was intended to mitigate the problem.

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

A Policy U-Turn

In response, the national police leadership body ordered that the confidence threshold required for potential matches be increased to a point where the disparity was greatly diminished.

However, this directive was overturned the following month following complaints from police that the adjusted system was generating fewer “investigative leads”. NPCC documents show the higher threshold reduced the proportion of queries that yielded possible identifications from over half to a just 14%.

Severe Disparities

Although the authorities refused to say what setting is now in operation, the recent independent review found the system could generate incorrect matches for Black women almost 100 times more frequently than for Caucasian women at specific configurations.

The ministry commented on these results: “The testing found that in a limited set of circumstances the algorithm is has a greater tendency to wrongly flag some demographic groups in its search results.”

Operational Effectiveness vs. Bias

Describing the effect of the brief increase to the system's accuracy setting, the police records note: “This adjustment significantly reduces the impact of bias across protected characteristics of ethnicity, generation and gender but had a substantially detrimental effect on police efficiency”. The papers further note that police units argued that “a previously useful tool returned results of questionable value”.

Wider Implementation Proposals

Meanwhile, the UK administration has opened a ten-week consultation on its plans to widen the use of biometric scanning systems. The minister for police the relevant minister has described the tool as the “biggest breakthrough since DNA matching”.

Expert and Oversight Concerns

Abimbola Johnson, chair of the advisory panel for the national policing equality strategy, commented: “We observed very little discussion through race action plan meetings of the technology deployment even with obvious cross-over with the strategy's goals.

“This disclosure show yet again that the pledges to combat discrimination policing has made via the race action plan are not being translated into broader operations. Independent assessments have warned that innovative tools are being implemented in a context where racial disparities, weak scrutiny 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 government representative stated: “We takes the conclusions of the study seriously and we have implemented changes. A new algorithm has been independently tested and acquired, which has no statistically significant bias. It will be trialled in the coming months and will be undergo further assessment.

“Our priority is protecting the public. This gamechanging technology will support officers to apprehend and prosecute offenders. There is officer review in every step of the procedure and no further action would be pursued without trained officers meticulously examining the output.”