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Law enforcement agencies across the UK effectively campaigned to use a face scanning system acknowledged as biased against women, youths, and members of minority ethnic backgrounds, after complaining that a more accurate 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 involves comparing a reference photograph of a suspect against a database of over 19 million custody photos to find possible hits.

Acknowledged Discrimination

The Home Office admitted last week that the technology was biased. This acknowledgment came after a study by the government's National Physical Laboratory found it misidentified people of Black and Asian heritage and females at significantly higher rates 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 biases in ethnicity and sex. Operational ease is a weak argument for overriding fundamental rights.”

Long-Standing Problem

Official papers show that this discriminatory flaw has been known about for over twelve months. Furthermore, law enforcement argued to overturn an earlier ruling that was designed to mitigate the problem.

Police bosses were notified of the system's bias in September 2024. The government-ordered NPL review found the system was had a higher probability to suggest incorrect matches for photos of females, Black people, and those under 40 years old.

A Policy U-Turn

In reaction, the national police leadership body mandated that the confidence threshold required for potential matches be raised to a level where the disparity was significantly reduced.

However, this decision was reversed the next month after forces complained that the modified technology was producing a lower number of “useful lines of inquiry”. Internal records show the higher threshold cut the number of queries that yielded possible identifications from 56% to a mere under 15%.

Profound Inequalities

Although the authorities refused to say what threshold is currently used, the recent independent review found the system could generate incorrect matches for women of Black heritage almost 100 times more often than for Caucasian women at specific configurations.

The Home Office stated on these findings: “The testing found that in a limited set of circumstances the algorithm is more likely to incorrectly include some demographic groups in its search results.”

Operational Effectiveness vs. Bias

Outlining the impact 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 race, age and gender but had a significant negative impact on police efficiency”. The documents add that forces complained that “a once effective tactic returned results of questionable value”.

Wider Implementation Proposals

Meanwhile, the government has opened a ten-week consultation on its plans to expand the use of biometric scanning systems. The minister for police the relevant minister has described the tool as the “most significant advance since DNA matching”.

Expert and Oversight Concerns

The chair of a police oversight board, chair of the independent scrutiny and oversight board for the police race action plan, said: “We observed very little consideration in race action plan meetings of the technology deployment despite clear relevance with the plan’s concerns.

“This disclosure demonstrate yet again that the pledges to combat discrimination the police has made via the race action plan are failing to be integrated into wider practice. Independent assessments have warned that innovative tools are being rolled out in a context where ethnic inequalities, weak scrutiny and poor data collection already persist.

“Any use of facial recognition must adhere to strict national standards, be independently scrutinised, and prove it diminishes rather than compounds racial disparity.”

Home Office Response

A government representative said: “The Home Office takes the findings of the study seriously and we have already taken action. A new algorithm has been externally evaluated and procured, which has no statistically significant bias. It will be tested in the coming months and will be subject to further assessment.

“The foremost aim is protecting the public. This revolutionary tool will support officers to put criminals and rapists behind bars. There is human involvement in each stage of the process and no further action would be pursued without specialist personnel meticulously examining the output.”