Territorial Sea Baselines

How It Works

Territorial sea baselines are the starting points from which a coastal state measures the breadth of its territorial sea under international law. These lines are typically drawn along the low-water line along the coast as marked on officially recognized charts. From these baselines, states can claim sovereignty over the waters extending up to 12 nautical miles seaward, known as the territorial sea.

There are different types of baselines: normal baselines follow the low-water line along the coast, while straight baselines can be drawn connecting appropriate points on the coast in places where the coastline is deeply indented or where there is a fringe of islands along the coast. In some cases, archipelagic baselines are used for archipelagic states, connecting the outermost points of the outermost islands.

Why It Matters

Territorial sea baselines are fundamental because they determine the maritime zones a state controls. The territorial sea allows a state to exercise sovereignty similar to that on land, including rights over natural resources, environmental protection, and law enforcement. Beyond the territorial sea, other maritime zones such as the contiguous zone and exclusive economic zone (EEZ) depend on these baselines for their measurement.

Disputes over baselines can lead to conflicts between states, especially where coastlines are complex or where strategic waterways are involved. Clear and internationally recognized baselines are essential for maintaining peaceful maritime boundaries and for the equitable use of marine resources.

Territorial Sea Baselines vs Maritime Boundaries

Territorial sea baselines are the lines from which maritime zones are measured, whereas maritime boundaries are the agreed or adjudicated borders between states' maritime zones. Baselines are drawn unilaterally by a coastal state according to international law, but maritime boundaries require negotiation or legal settlement between neighboring states.

Real-World Examples

Norway uses straight baselines along its fjord-indented coastline to measure its territorial sea, a practice recognized under the United Nations Convention on the Law of the Sea (UNCLOS). Conversely, the United States generally uses normal baselines but has drawn straight baselines around some groups of islands.

Common Misconceptions

A common misconception is that territorial sea baselines are always the low-water line along the coast. While this is true for normal baselines, straight baselines may connect points across bays or between islands, which can extend the baseline seaward. Another misunderstanding is that baselines can be arbitrarily drawn; in reality, they must comply with international law, particularly UNCLOS, and be justifiable geographically and historically.

Legal Framework

The United Nations Convention on the Law of the Sea (UNCLOS) codifies the rules for establishing territorial sea baselines in Articles 5 to 11. It provides criteria for when straight baselines may be used and limits on their application to prevent excessive claims. States are required to publish charts or lists of geographical coordinates of their baselines to notify other states and the international community.

Implications for Diplomacy and International Relations

Understanding territorial sea baselines is crucial in diplomacy because they impact maritime sovereignty, resource rights, and security. Disputes over baselines can escalate into diplomatic tensions or conflicts, making clear legal knowledge and negotiation skills vital for political scientists and diplomats working in maritime affairs.