🔗 Share this article

Police forces across the United Kingdom successfully lobbied to use a facial recognition system known to be discriminatory against women, youths, and individuals from ethnic minority groups, following complaints that a less biased version generated a reduced number of investigative leads.

The Technology in Practice

UK forces utilize the police national database (PND) to carry out searches using historical face recognition. This procedure involves comparing a “probe image” of a person of interest against a database of more than 19 million custody photos to identify potential matches.

Admitted Bias

The UK interior ministry admitted last week that the technology was flawed. This acknowledgment followed a study by the National Physical Laboratory (NPL) determined it misidentified people of Black and Asian heritage and women at much greater frequency than white men. The ministry stated it “had acted on the findings”.

“This raises the question of whether this technology only becomes effective if users accept discrimination in ethnicity and gender. Convenience is a weak argument for disregarding fundamental rights.”

Long-Standing Problem

Official papers show that this discriminatory flaw has been recognized for more than a year. Furthermore, police forces lobbied to reverse an earlier ruling that was designed to mitigate the problem.

Police bosses were notified of the system's bias in September 2024. The Home Office-commissioned laboratory study found the system was more likely to suggest false positives for images depicting women, Black people, and those under 40 years old.

A Reversed Decision

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

However, this directive was reversed the next month after forces complained that the adjusted system was producing fewer “useful lines of inquiry”. Internal records show the higher threshold cut the number of queries resulting in potential matches from 56% to a mere 14%.

Profound Inequalities

Although the Home Office and NPCC declined to specify what setting is now in operation, the latest NPL study found the system could produce incorrect matches for Black women nearly a hundred times more frequently than for Caucasian women at certain settings.

The Home Office commented on these results: “The testing identified 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 impact of the brief increase to the system's accuracy setting, the police records state: “This adjustment significantly reduces the effect of bias across legally safeguarded attributes of ethnicity, age and sex but had a substantially detrimental effect on operational effectiveness”. The documents add that police units complained that “a once effective tactic returned outcomes of limited benefit”.

Wider Implementation Proposals

Meanwhile, the UK administration has launched a two-and-a-half-month public review on its plans to expand the use of biometric scanning systems. Policing minister the relevant minister has labeled the technology as the “biggest breakthrough since DNA matching”.

Expert and Oversight Concerns

The chair of a police oversight board, chair of the advisory panel for the national policing equality strategy, commented: “We observed very little consideration in equality strategy sessions of the facial recognition rollout even with obvious cross-over with the strategy's goals.

“This disclosure demonstrate yet again that the anti-racism commitments the police has undertaken via the race action plan are not being translated into broader operations. Independent assessments have cautioned that innovative tools are being implemented in a context where racial disparities, weak scrutiny and poor data collection already persist.

“Any use of this technology must meet rigorous official guidelines, be subject to external review, and demonstrate it diminishes rather than compounds racial disparity.”

Official Statement

A Home Office spokesperson stated: “We treat the conclusions of the report seriously and we have implemented changes. A new algorithm has been externally evaluated and acquired, which has no statistically significant bias. It will be trialled early next year and will be subject to further assessment.

“Our priority is ensuring public safety. This revolutionary tool will support officers to apprehend and prosecute offenders. There is human involvement in each stage of the process and no arrest or charge would be taken without trained officers meticulously examining the output.”