Regulatory sandboxes under scrutiny: five dimensions in need of attention

Regulatory sandboxes have become a key instrument in EU digital governance, and substantial academic research has mapped their legal framework and assessed their operational effectiveness. This paper does not revisit that ground. Instead, it identifies a set of structurally important questions that have been inadequately investigated in the existing literature. These questions address the fundamental issue of whether sandboxes can function as legitimate, effective, and democratically accountable instruments of public law. The analysis is structured around five dimensions. The first concerns the co-regulatory shift that sandboxes represent, as well as the associated legitimacy issues and risks of regulatory capture. The second dimension examines the conditions under which sandboxes can facilitate genuine regulatory learning rather than merely bilateral information exchange. The third dimension addresses communication as a critical yet systematically underspecified governance function throughout the sandbox lifecycle. The fourth dimension examines the territorial aspect of sandbox governance, where a significant gap remains between legal possibility and operational readiness. The fifth dimension explores the relationship between sandbox design and the operational protection of fundamental rights. Together, these five dimensions reveal that sandboxes are not merely governance instruments; they also mirror the structural tensions running through EU digital governance. Improving them requires addressing issues that extend well beyond the instrument itself at a time when the current governance choices will indelibly shape how the digital domain is governed and organized.