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Police forces across the United Kingdom effectively campaigned to use a face scanning system acknowledged as discriminatory against women, youths, and individuals from ethnic minority groups, following complaints that a less biased version generated fewer investigative leads.

The Technology in Practice

British police use the national police database to carry out searches using historical face recognition. This procedure involves comparing a “probe image” of a suspect against a database of more than 19 million custody photos to find potential matches.

Admitted Bias

The Home Office conceded last week that the system was flawed. This acknowledgment came after a study by the government's National Physical Laboratory found it incorrectly matched people of Black and Asian heritage and women at much greater frequency than white men. The Home Office stated it “took steps on the findings”.

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

Long-Standing Problem

Official papers reveal that this discriminatory flaw has been recognized for over twelve months. Furthermore, police forces argued to overturn an initial decision that was designed to address the problem.

Police bosses 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 aged 40 and under.

A Reversed Decision

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

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

Profound Inequalities

Although the authorities refused to say what threshold is now in operation, the latest independent review found the system could produce incorrect matches for women of Black heritage almost 100 times more frequently than for Caucasian women at certain settings.

The ministry stated on these findings: “The testing found that in a specific scenarios the algorithm is more likely to wrongly flag some population segments in its search results.”

Operational Effectiveness vs. Bias

Describing the effect of the brief increase to the system's confidence threshold, the police records state: “This adjustment greatly lessens the effect of discrimination across protected characteristics of ethnicity, generation and sex but had a substantially detrimental effect on operational effectiveness”. The documents further note that forces argued that “a previously useful tool returned results of questionable value”.

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 facial recognition technology. 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: “There was scant discussion in equality strategy sessions of the technology deployment despite clear relevance with the plan’s concerns.

“These revelations demonstrate yet again that the pledges to combat discrimination policing has made through the race action plan are not being translated into broader operations. Independent assessments have cautioned that new technologies are being rolled out in a context where racial disparities, inadequate oversight and poor data collection continue to exist.

“All deployment of this technology must meet strict national standards, be subject to external review, and prove it reduces rather than compounds ethnic bias.”

Home Office Response

A government representative said: “The Home Office takes the findings of the report seriously and we have implemented changes. A new algorithm has been externally evaluated and acquired, which has demonstrated no measurable discrimination. It will be trialled early next year and will be undergo evaluation.

“Our priority is ensuring public safety. This gamechanging technology will support officers to put criminals and rapists behind bars. There is officer review in every step of the process and no arrest or charge would be taken without specialist personnel carefully reviewing the output.”