Law of the sea

International Law · Subjects and territory. The idea in plain words, the rules to remember, the mistake to avoid and a worked example, written and checked by Mega Lecture.

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The idea

The UN Convention on the Law of the Sea (UNCLOS) 1982 divides the sea into zones measured from baselines, normally the low-water line along the coast. The nearer a zone is to the coast, the stronger the coastal state's rights. In the territorial sea the state has sovereignty; in the exclusive economic zone (EEZ) it has only sovereign rights over resources; on the high seas no state has sovereignty.

Other states keep rights in each zone. Foreign ships have a right of innocent passage through the territorial sea, and freedom of navigation in the EEZ and on the high seas. The deep seabed beyond national jurisdiction belongs to no state.

Rules to remember

Territorial sea: up to 12 nautical miles from the baselines; sovereignty, subject to innocent passage.
Contiguous zone: up to 24 nautical miles; control over customs, fiscal, immigration and sanitary matters.
EEZ: up to 200 nautical miles; sovereign rights over living and non-living resources.
Continental shelf: rights over seabed resources exist automatically, without occupation or proclamation.
Innocent passage: continuous and expeditious, not prejudicial to peace, good order or security; submarines must surface and show their flag.
High seas freedoms (Article 87): navigation, overflight, laying cables and pipelines, artificial islands, fishing, scientific research; ships are under flag-state jurisdiction.
The Area (deep seabed) and its resources are the common heritage of mankind.

Common mistake

Students say the coastal state has sovereignty over the EEZ. It has sovereign rights over resources only; ships of all states still enjoy freedom of navigation there. All zones are measured from the baselines, so the contiguous zone ends at 24 nautical miles, not 12 + 24.

Worked example

A foreign cargo ship is 18 nautical miles from State X's baselines, heading for X's coast. X's coastguard has good reason to believe it is about to smuggle goods into X. May X act, and in which zone is the ship?

18 nautical miles is beyond the 12-mile territorial sea, so the ship is not in waters under X's sovereignty.
It is within 24 nautical miles of the baselines, so it is in the contiguous zone.
In that zone a coastal state may exercise the control needed to prevent breaches of its customs laws within its territory or territorial sea.

Answer: Yes. The ship is in the contiguous zone, where X may act to prevent a breach of its customs laws.

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