International Law and Power Politics in the South China Sea: The Implications of China’s Non-Compliance for Regional Security

The South China Sea is a focal point for tensions between international law, great-power politics, and regional security in the Asia-Pacific region. This article critically analyses the 2016 arbitral award in Philippines v. China under the United Nations Convention on the Law of the Sea (UNCLOS) and considers the implications of China’s persistent defiance. Drawing on a multidisciplinary approach combining legal analysis, International Relations theory, and geopolitics, the paper argues that the arbitration did clarify legal entitlements (dismissing China’s expansive ‘nine-dash line’ claims, clarifying the legal status of maritime features, and recognising the Philippines’ EEZ rights), but has not led to a modification of China’s strategic conduct. The paper illustrates how China’s militarization of artificial islands, control over sea lanes, and wielding of economic and diplomatic influence represent limits to what international law enforcement can compel when a major power is its subject. These trends highlight the friction between written law and power politics, expose the fragility of UNCLOS enforcement mechanisms, and reveal the potential in multilaterally-driven diplomacy, regional security architecture, and integrated governance approaches that address legal, environmental, and strategic concerns. The South China Sea case thus provides lasting lessons about the efficacy of international maritime law, the role of smaller states in formulating legal claims, and the prospects for a rules-based order in contested waters. Received: 18 November 2025 /Accepted: 30 December 2025 /Published:January 2026