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Police forces across the United Kingdom successfully lobbied to deploy a face scanning system known to be discriminatory against females, youths, and members of minority ethnic backgrounds, following complaints that a less biased version generated a reduced number of potential suspects.

How the System Works

UK forces utilize the police national database (PND) to conduct searches using historical face recognition. This procedure involves matching a reference photograph of a person of interest against a database of over 19 million custody photos to find potential matches.

Acknowledged Discrimination

The UK interior ministry admitted last week that the system was biased. This acknowledgment followed a study by the government's National Physical Laboratory determined it misidentified people of Black and Asian heritage and women at significantly higher rates than Caucasian males. The Home Office stated it “took steps on the findings”.

“This raises the question of whether facial recognition only becomes effective if users tolerate biases in ethnicity and sex. Convenience is a weak argument for overriding basic freedoms.”

Known Issue

Official papers reveal that this bias has been known about for more than a year. Furthermore, law enforcement argued to overturn an earlier ruling that was intended to address the problem.

Police bosses were notified of the system's bias in September 2024. The government-ordered NPL review concluded the system was more likely to produce false positives for photos of women, individuals of Black ethnicity, and those aged 40 and under.

A Policy U-Turn

In response, the national police leadership body ordered that the accuracy setting required for possible hits be increased to a point where the disparity was significantly reduced.

However, this directive was overturned the next month after forces complained that the adjusted system was generating a lower number of “investigative leads”. NPCC documents show the higher threshold reduced the proportion of searches that yielded potential matches from over half to a just under 15%.

Profound Inequalities

Although the Home Office and NPCC refused to say what threshold is currently used, the latest NPL study discovered 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 results: “Our evaluation identified that in a limited set of circumstances the algorithm is more likely to wrongly flag some demographic groups in its search results.”

Operational Effectiveness vs. Bias

Outlining the impact of the brief increase to the system's confidence threshold, the police records note: “This adjustment significantly reduces the effect of bias across protected characteristics of ethnicity, age and gender but had a significant negative impact on operational effectiveness”. The documents add that police units argued that “a once effective tactic now delivered results of limited benefit”.

Broader Rollout Plans

Meanwhile, the government has launched a two-and-a-half-month consultation on its plans to expand the use of biometric scanning systems. The minister for police the relevant minister has described the technology as the “biggest breakthrough since genetic fingerprinting”.

Criticism from Advisors and Monitors

The chair of a police oversight board, chair of the advisory panel for the police race action plan, commented: “We observed very little discussion through equality strategy sessions of the technology deployment even with clear relevance with the strategy's goals.

“These revelations show yet again that the anti-racism commitments the police has made through the race action plan are not being translated into wider practice. Our reports have cautioned that innovative tools are being rolled out in a landscape where racial disparities, weak scrutiny and poor data collection continue to exist.

“Any use of facial recognition must adhere to rigorous official guidelines, be subject to external review, and demonstrate it diminishes rather than exacerbates racial disparity.”

Official Statement

A government representative stated: “We takes the findings of the report 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.

“Our priority is protecting the public. This gamechanging technology will assist officers to put criminals and rapists behind bars. There is officer review in every step of the procedure and no arrest or charge would be pursued without trained officers meticulously examining the results.”