The Role of the International Court of Justice in Shaping Customary International Law
The Role of the International Court of Justice in Shaping Customary International Law

Summary/Abstract: Customary international law (CIL) stands as a cornerstone of the international legal order. Historically rooted in state practices, CIL has evolved from organic norm development to a dynamic force shaped by multilateral frameworks, reflecting the international community’s evolving consensus. This paper examines CIL’s primacy, aiming to elucidate its theoretical underpinnings, historical precedence, and transformative influence through the International Court of Justice (ICJ). Employing doctrinal and historical analysis of judicial decisions, state practices, and legal frameworks, it traces CIL’s trajectory from early state consent to modern collective commitments, highlighting the ICJ’s pivotal role in norm crystallisation. The study explores how CIL’s dual-track approach, balancing rapid norm formation with practice-based stability, addresses global challenges like decolonisation and cyber warfare. By affirming universal standards while exercising strategic restraint, the ICJ ensures CIL’s adaptability and coherence. Structured across four thematic sections, this analysis illuminates the ICJ’s nuanced engagement with CIL, offering insights into its enduring contribution to a responsive international legal system, while advocating for clearer judicial standards to sustain its relevance.

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