Yogyakarta, June 29, 2026 — As part of the Short Course “ASEAN and the South China Sea”, Assoc. Prof. Dr. Mohd Hazmi Mohd Rusli from the Faculty of Syariah and Law, Universiti Sains Islam Malaysia (USIM), delivered a lecture exploring the historical evolution of the law of the sea and its continuing relevance to contemporary maritime disputes. The lecture traced the development of maritime governance from the competing concepts of mare liberum and mare clausum to the adoption of the United Nations Convention on the Law of the Sea (UNCLOS) as the modern constitution for the oceans. It also examined the principle of uti possidetis juris, demonstrating how colonial boundaries, historical treaties, and imperial administration continue to shape maritime sovereignty, jurisdiction, and boundary delimitation in Southeast Asia.
Building on this historical foundation, the lecture critically examined the relationship between history, international law, and geopolitics in shaping present-day maritime disputes. It argued that many contemporary conflicts cannot be understood solely through the provisions of UNCLOS, but must also be viewed in light of colonial legacies, competing historical narratives, and strategic rivalry among states. Using the Straits of Malacca, the Strait of Hormuz, and the South China Sea as case studies, the lecture illustrated how these strategically important waterways continue to test the balance between the interests of coastal states and the international community. While states have legitimate security and sovereign interests, these must be carefully balanced with the principle of freedom of navigation. In this regard, UNCLOS represents a carefully negotiated compromise between mare liberum and mare clausum, providing a legal framework that accommodates both interests as long as states faithfully adhere to the Convention.
The lecture further examined Malaysia’s legal position in the South China Sea, explaining the distinction between sovereignty and sovereign rights, the legal basis of Malaysia’s maritime entitlements under UNCLOS, and the significance of the 2016 South China Sea Arbitral Award in clarifying the interpretation of the Convention. Participants were encouraged to critically reflect on whether international law alone can effectively manage maritime disputes when legal norms are increasingly challenged by geopolitical competition.
The lecture concluded by emphasising that the oceans should not become arenas of confrontation but spaces for peace, cooperation, and shared prosperity. While we cannot change the colonial past that shaped many of today’s maritime boundaries and disputes, we can shape the future by respecting international law, resolving differences through peaceful means, and ensuring that the seas continue to be used exclusively for peaceful purposes. He added, “Upholding UNCLOS remains essential to preserving a stable, predictable, and rules-based maritime order for present and future generations.”