The EHDS Regulation: Health Data at the Crossroads of Patient Autonomy, Data Protection, and Innovation.

Digitalization and data-driven research are widely recognized as key drivers of innovation in healthcare, with the potential to improve clinical outcomes, accelerate research, and support evidence-based policymaking. Nevertheless, across jurisdictions, obstacles such as fragmented data governance, limited interoperability, and tensions between data protection and data reuse continue to hinder the effective use of health data. The Regulation on the European Health Data Space (Regulation (EU) 2025/327) represents a significant shift in EU health data governance. It seeks to create a single European market for health data by introducing harmonized rules, shared technical standards, and new institutional structures, while simultaneously reinforcing patients' rights, access to their data, and control over its use. This paper aims to provide a clear and systematic account of the Regulation for a broad international and interdisciplinary audience. It situates the legal piece within its broader political and legal context, highlighting the factors that shaped its design and providing a comprehensive analysis of its core concepts. Using the patient opt-out regime as a case study, the paper critically examines the enduring tensions between safeguarding fundamental rights, ensuring patient autonomy, and fostering innovation and economic objectives, all while accommodating national preferences.