This part focuses on the foundational aspects of international human rights law, exploring its theoretical, historical, and philosophical underpinnings. It examines the evolution of human rights ideas, the influence of various philosophical traditions, and the ongoing debates about the nature and universality of human rights. The sections address the epistemological ruptures between philosophy and law, and between law and justice, highlighting the challenges in reconciling these perspectives within a coherent human rights framework. The part also delves into normative pluralism, discussing the coexistence and interaction of multiple legal systems and norms within the global human rights framework. It covers treaty-based structures, customary international law, general principles of law, and the role of judicial decisions and soft law instruments. By critically analyzing these foundational elements, this part aims to provide a deeper understanding of the principles and values that underpin international human rights law and to highlight the complexities and nuances involved in defining and protecting human rights in diverse cultural and legal contexts.