Reconstruction of the Legality of the Declaration of Independence of Catalonia from Spain from the Perspective of International Law and Constitutional Forensics

Abstract

This study analyzes the legality of Catalonia's declaration of independence from Spain through the perspectives of international law and constitutional forensics. The main problem of this study lies in the conflict between the principle of the right to self-determination recognized in international law and the principle of the territorial integrity of a sovereign state and the supremacy of the national constitution. This study aims to reconstruct the legal basis of Catalonia's declaration of independence by examining international legal norms, Spanish constitutional provisions, and comparative constitutional practices. The method used is normative legal research with legislative, conceptual, historical, and case study approaches. The analysis is conducted on international instruments, decisions of the International Court of Justice, the 1978 Spanish Constitution, and the dynamics of the 2017 Catalan referendum. The results of this study indicate that from an international legal perspective, the right to self-determination is more directed at the context of decolonization, foreign occupation, or systematic oppression, so it does not automatically legitimize Catalonia's secession. Meanwhile, from a constitutional forensics perspective, Catalonia's declaration of independence contradicts the Spanish constitutional order, which affirms the unity of the state and does not provide for a unilateral secession mechanism. However, this study also found that a repressive approach alone does not resolve political demands and regional identities. Therefore, the reconstruction of legality needs to be directed toward a constitutional solution model through political dialogue, autonomy reform, or a legally agreed referendum. This study emphasizes the importance of harmonizing democratic legitimacy, constitutional supremacy, and international legal principles in addressing contemporary separatist movements.