EU integration and fundamental rights protection.

This work explores the legal dimension of European integration, focusing particularly on the constitutional guarantees of fundamental rights and freedoms within a multilevel governance system. It provides a scientific analysis of the existing mechanisms for protecting rights in the European Union, the Spanish legal system, and the international framework, notably the Council of Europe.

By addressing both regulatory and jurisdictional safeguards—as well as the so-called guarantee institutions—this study offers a comprehensive overview of the European multilevel legal order. Framed within the theory of multilevel constitutionalism, it serves as a valuable guide to understanding how rights are protected across different legal spheres, with a special focus on the Spanish context.