UNCLOS

The United Nations Convention on the Law of the Sea is the overarching legal framework governing how nations may use the seas and their resources. Adopted in 1982 and widely ratified, it is frequently described as a constitution for the oceans because it brings together in one comprehensive treaty the rules on where a coastal state's authority extends, what rights other states have to navigate and to exploit resources, and how disputes are to be settled. It provides the legal backdrop against which the more technical shipping conventions of the IMO operate.

UNCLOS defines a series of maritime zones measured from the coast. Within the territorial sea, extending up to twelve nautical miles, the coastal state has sovereignty, subject to the right of innocent passage that allows foreign ships to transit peacefully. Beyond it lie the contiguous zone, where the state may enforce certain laws, and the exclusive economic zone, extending up to two hundred nautical miles, where the coastal state has rights over natural resources such as fish and seabed minerals while other states retain freedoms of navigation and overflight. Further out lies the high seas, open to all, and the convention also addresses the continental shelf, archipelagic waters and transit passage through international straits.

For shipping, UNCLOS matters because it guarantees the freedoms of navigation on which international trade depends, defines the duties of flag states over their ships, and provides the framework for jurisdiction over matters such as pollution, piracy and marine scientific research. It establishes institutions including the International Tribunal for the Law of the Sea to resolve disputes. While the day-to-day safety and pollution rules come from IMO conventions, those instruments sit within the rights and obligations that UNCLOS lays down, making it foundational to the legal order of the oceans.