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Law enforcement agencies across the UK successfully lobbied to deploy a face scanning system known to be biased against females, young people, and members of minority ethnic backgrounds, after complaining that a less biased version generated fewer investigative leads.

The Technology in Practice

UK forces use the national police database to conduct searches using historical face recognition. This process entails matching a “probe image” of a person of interest against a database of over 19 million mugshots to find potential matches.

Acknowledged Discrimination

The UK interior ministry admitted last week that the system was flawed. This admission followed a study 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 said it “had acted on the findings”.

“This raises the question of whether facial recognition only becomes useful if users tolerate biases in race and sex. Operational ease is a weak argument for disregarding basic freedoms.”

Long-Standing Problem

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

Senior officers were notified of the algorithmic discrimination in September 2024. The Home Office-commissioned NPL review concluded the system was more likely to produce incorrect matches for photos of women, individuals of Black ethnicity, and those under 40 years old.

A Policy U-Turn

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

However, this directive was reversed the following month following complaints from police that the adjusted system was generating a lower number of “useful lines of inquiry”. NPCC documents indicate the higher threshold cut the proportion of queries that yielded potential matches from over half to a mere 14%.

Severe Disparities

Although the Home Office and NPCC refused to say what threshold is now in operation, the recent NPL study discovered the system could produce false positives for Black women almost 100 times more frequently than for white women at specific configurations.

The Home Office commented on these findings: “Our evaluation found that in a specific scenarios the software is has a greater tendency to wrongly flag some demographic groups in its search results.”

Balancing Utility and Fairness

Outlining the effect of the brief increase to the system's accuracy setting, the police records note: “This adjustment significantly reduces the impact of discrimination across legally safeguarded attributes of race, age and sex but had a substantially detrimental effect on police efficiency”. The documents add that forces argued that “a once effective tactic returned outcomes of questionable value”.

Broader Rollout Plans

Meanwhile, the UK administration has launched a two-and-a-half-month consultation on its plans to widen the use of biometric scanning systems. Policing minister the relevant minister has labeled the tool as the “most significant advance since DNA matching”.

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, said: “We observed scant consideration through race action plan meetings of the facial recognition rollout despite obvious cross-over with the plan’s concerns.

“These revelations demonstrate yet again that the anti-racism commitments policing has undertaken through the equality initiative are failing to be integrated into wider practice. Our reports have cautioned that innovative tools are being implemented in a context where racial disparities, inadequate oversight and poor data collection already persist.

“Any use of this technology must adhere to rigorous official guidelines, be independently scrutinised, and demonstrate it diminishes rather than exacerbates ethnic bias.”

Home Office Response

A Home Office spokesperson said: “We takes the conclusions of the report seriously and we have already taken action. A updated software has been externally evaluated and procured, which has no statistically significant bias. It will be tested early next year and will be subject to further assessment.

“The foremost aim is protecting the public. This gamechanging technology will assist police to put criminals and rapists behind bars. There is officer review in every step of the procedure and no further action would be taken without specialist personnel meticulously examining the results.”