Police Scotland’s custody photographs taken between 2019 and 2024 are suffering from significant quality issues that render them largely ineffective for facial recognition technology, according to a new report from the Scottish Biometrics Commissioner. The technical limitations could potentially result in crimes going undetected and raise serious concerns about the effectiveness of police investigations.
Dr. Brian Plastow, who has been actively monitoring Police Scotland’s biometric practices as the Scottish Biometrics Commissioner, revealed that a “sizeable proportion” of custody images are unsuitable for facial searching technology software. This finding marks a shift in tone from his earlier praise of Police Scotland’s approach to biometric technology regulation in May 2024.
The technical problems stem from a software issue causing custody images to be captured at a lower than recommended minimum size, with subsequent compression further degrading their quality. This has severely impacted the effectiveness of facial recognition searches within the Police National Database (PND).
Between April 2023 and March 2024, Police Scotland conducted 3,813 facial searches via the PND, but approximately 98 percent of these searches failed to produce potential matches. “This suggests that the technology’s current application may not be delivering significant operational value in the majority of cases,” Dr. Plastow noted.
The issue comes amid ongoing concerns about Police Scotland’s biometric data management. While the force has never implemented live facial recognition technology, it uses Retrospective Image Search Technology (RIST) through two databases: the Police National Database and the Child Abuse Image Database (CAID).
The report outlines four key recommendations for Police Scotland, including developing specific policies for retrospective image search technologies, conducting training needs analysis, improving data collection methods, and enhancing public understanding of these technologies.
Dr. Plastow emphasized the delicate nature of addressing these technical issues: “Extreme caution must be exercised with any retrospective ICT fix to uncompress these images. If they cannot be fully restored to their original format, the reliability of the data could be significantly compromised.”
The news follows Police Scotland’s recent efforts to improve transparency in biometric data collection, including the introduction of informational leaflets for individuals in custody about their biometric data collection practices.
Sources: BBC, Computer Weekly, The Scotsman
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March 25, 2025 – by Ali Nassar-Smith
