This article analyses the preliminary questions referred by the Rotterdam District Court to the CJEU concerning the interplay between the Dutch WAMCA regime for collective actions with the GDPR, particularly regarding admissibility requirements for claim organisations and the opt-out basis. It explores the legal tension between national procedural rules and EU data protection law, the implications for ongoing high-profile class actions, and the broader impact on collective redress mechanisms across the EU. The forthcoming CJEU decision is expected to provide crucial guidance on the future of GDPR collective actions and the balance between access to justice and procedural safeguards.