From Law in the Books to Law in Action, Regulatory Rationalities in Health Data Governance A Socio-Legal Analysis of Health Data Regulators in France under the European Framework[De la loi sur le papier à la loi en action : les rationalités réglementaires dans la gouvernance des données de santé Une analyse socio-juridique des autorités de régulation des données de santé en France dans le cadre européen]

This article examines how health data governance in France is being reshaped by European regulation (GDPR, EHDS, AI Act, NIS2, CRA) and the digital transformation of healthcare. Drawing on 28 semi-structured interviews with four categories of actors, producers, disseminators, users, and decision-makers, it explores how regulatory obligations are interpreted and enacted in practice. Using a mixed socio-legal methodology combining qualitative analysis and quantitative indicators, the study maps tensions across the data access chain. Findings show broad support for including social determinants within the scope of health data (91.7%), conditional confidence in artificial intelligence when embedded in secure environments (66.7%), and significant silence regarding cybersecurity responsibilities (79.2%). The analysis reveals a persistent gap between law on the books and law in action: producers and researchers often experience regulation as constraint, whereas decision-makers frame it as a source of legitimacy and accountability. These divergent pragmatic, procedural, scientific, and normative rationalities shape both compliance practices and innovation pathways. The article argues that European health data governance increasingly seeks to reconcile openness with trust through safeguarded data sharing, while new technologies challenge existing notions of privacy, responsibility, and representativeness. It concludes by calling for a more integrated and adaptive model of governance combining legal clarity, transparent cybersecurity, distributed AI accountability, and participatory policy maker.