Law of the Sea

THE LAW OF THE SEA is a compilation of international and national laws regulating the demarcation of areas of maritime jurisdiction appertaining to maritime states. While its origins were military and defensive today it focuses on respective rights of resource exploitation—oil and minerals as well as fisheries. The importance of international innocent passage via geopolitical choke points and along multinational rivers also is relevant.

The oceans had long been subject to the freedom of the seas and innocent passage doctrine, a principle put forth in the 17th century designed essentially to limit national rights and jurisdiction over the oceans to a narrow belt of sea surrounding a nation’s coastline. The remainder of the seas was proclaimed to be free to all and belonging to none. While this situation prevailed into the 20th century, by mid-century there was an impetus to extend national claims over offshore resources.

Law of the Sea

There was growing concern over the toll taken on coastal fish stocks by long-distance fishing fleets and over the threat of pollution and wastes from transport ships and oil tankers carrying noxious cargoes that plied sea routes across the globe. The hazard of pollution was ever present, threatening coastal resorts and all forms of ocean life. The navies of the maritime powers were competing to maintain a presence across the globe on the surface waters and even under the sea.

All maritime countries have claimed some part of the seas beyond their shores as part of their sovereign territory, a zone of protection to be patrolled against smugglers, warships, and other intruders. At its origin, the basis of the claim of coastal states to a belt of the sea was the principle of protection; during the 17th and 18th centuries, another principle gradually evolved: that the extent of this belt should be measured by the power of the littoral sovereign to control the area.

In the 18th century, the so-called cannon-shot rule gained wide acceptance in Europe. Coastal states were to exercise dominion over their territorial seas as far as projectiles could be fired from cannon based on the shore. According to some scholars, in the 18th century the range of land-based cannons was approximately one marine league, or three nautical miles. It is believed that on the basis of this formula developed the traditional 3-mi (4.8-km) territorial sea limit.

By the late 1960s, a trend to a 12-mi (19.3-km) territorial sea had gradually emerged throughout the world, with a great majority of nations claiming sovereignty out to that seaward limit. However, the major maritime and naval powers clung to a 3-mi limit on territorial seas, primarily because a 12-mi limit would effectively close off and place under national sovereignty more than 100 straits used for international navigation.

In 1973, an international conference aimed at reaching an agreement was convened in New York. Nine years later in 1982, it adopted a constitution for the seas: the United Nations Convention on the Law of the Sea. During those nine years, representatives of more than 160 states sat down and discussed the issues and bargained and traded national rights and obligations in the course of the marathon negotiations that produced the convention.

Among the more important aspects of the convention are navigational rights, territorial sea limits, economic jurisdiction, legal status of resources on the seabed beyond the limits of national jurisdiction, passage of ships through narrow straits, conservation and management of living marine resources, protection of the marine environment, a marine research regime, and, a more unique feature, a binding procedure for settlement of disputes between states. In short, the convention is an unprecedented attempt by the international community to regulate all aspects of the resources of the sea and uses of the ocean and thus bring order to one of mankind’s very source of life.


Territorial waters are the belt of sea adjacent to shores that states claim as being under their immediate territorial jurisdiction, subject only to a right of innocent passage by vessels of all nations. As to the breadth of the belt and the exact nature of this right of innocent passage, however, there is still much controversy. The 3-mi limit recognized and practiced by Great Britain, FRANCE, and the UNITED STATES seems to have been derived from the cannon range of the period, when it was adopted between Great Britain and the United States, toward the close of the 18th century.

The doctrine satisfied a requirement of the time and became a maxim of international law throughout northern Europe, both for the protection of shore fisheries and for the assertion of the immunity of adjacent waters of neutral states from acts of war between belligerent states. GERMANY still holds, in principle, to this varying limit of cannon range. NORWAY has never agreed to the 3-mi limit, maintaining that the special configuration of its coastline necessitates the exercise of jurisdiction over a belt of 4 mi (6.4 km). SPAIN lays claim to jurisdiction over 6 mi (9.6 km) from its shores.

Traditionally, smaller states and those not possessing large, ocean-going navies or merchant fleets favored a wide territorial sea in order to protect their coastal waters from infringements by those states that did. Naval and maritime powers, on the other hand, sought to limit the territorial sea as much as possible, in order to protect their fleets’ freedom of movement.

As the work of the conference progressed, the move toward a 12-mi territorial sea eventually gained universal acceptance. Within this limit, states are in principle free to enforce any law, regulate any use, and exploit any resource. The convention retains for naval and merchant ships the right of innocent passage through the territorial seas of a coastal state. This means, for example, that a Japanese ship, picking up oil from a gulf state, would not have to make a 3,000- mi (5,000-km) detour in order to avoid the territorial sea of INDONESIA, provided passage is not detrimental to Indonesia and does not threaten its security or violate its laws.

In addition to their right to enforce any law within their territorial seas, coastal states are empowered to implement certain rights in an area beyond the territorial sea, extending for 24 nautical miles from their shores, for the purpose of preventing certain violations and enforcing police powers. This area, known as the contiguous zone, may be used by a coast guard or its naval equivalent to pursue and, if necessary, arrest and detain suspected drug smugglers, illegal immigrants, and customs or tax evaders violating the laws of the coastal state within its territory or the territorial sea.

Largely ignored were the problems such as multiple states claiming the same maritime zones, as in the South China and East China seas, and disputes over control of the sea when two nations, such as CHINA and TAIWAN, claim different governments. In short, the devil is in the geographic and geopolitical details.


The exclusive economic zone (EEZ) is one of the most revolutionary features of the convention, and one that already has had a profound impact on the management and conservation of the resources of the oceans. Simply put, it recognizes the right of coastal states to jurisdiction over the resources of some 38 million square nautical miles of ocean space. To the coastal state falls the right to exploit, develop, manage, and conserve all resources—fish or oil, gas or gravel, nodules or sulphur—to be found in the waters, on the ocean floor, and in the subsoil of an area extending 200 mi (321.8 km) from its shore.

The EEZs are a generous endowment indeed. About 87 percent of all known and estimated hydrocarbon reserves under the sea fall under some national jurisdiction as a result. So too will almost all known and potential offshore mineral resources, excluding the mineral resources (mainly manganese nodules and metallic crusts) of the deep ocean floor beyond national limits. And whatever the value of the nodules, it is the other nonliving resources, such as hydrocarbons, that represent the presently attainable and readily exploitable wealth.

The most lucrative fishing grounds, too, are predominantly the coastal waters. This is because the richest phytoplankton pastures lie within 200 miles of the continental masses. Phytoplankton, the basic food of fish, is brought up from the deep by currents and ocean streams at their strongest near land and by the upwelling of cold waters where there are strong offshore winds. The desire of coastal states to control the fish harvest in adjacent waters was a major driving force behind the creation of the EEZs.

Today, the benefits brought by the EEZs are more clearly evident. Already 86 coastal states have economic jurisdiction up to the 200-mi limit. As a result, almost 99 percent of the world’s fisheries now fall under some nation’s jurisdiction. Also, a large percentage of world oil and gas production is offshore. Many other marine resources also fall within coastal-state control. This provides a long-needed opportunity for rational, well-managed exploitation under an assured authority.

Coastal states also have certain rights in the CONTINENTAL SHELF, comprising the seabed and its subsoil that extend beyond the limits of its territorial sea throughout the natural prolongation of its land territory to the outer edge of the continental margin, or to a distance of 200 mi from the baselines from which the territorial sea is measured, where the outer edge of the continental margin does not extend up to that distance.

In cases where the continental margin extends further than 200 mi, nations may claim jurisdiction up to 350 mi (482.8 km) from the baseline or 100 mi (161 km) from the 8,202-ft or 2,500-m depth, depending on certain criteria such as the thickness of sedimentary deposits. These rights would not affect the legal status of the waters or that of the airspace above the continental shelf. To counterbalance the continental shelf extensions, coastal states must also contribute to a system of sharing the revenue derived from the exploitation of mineral resources beyond 200 mi. These payments or contributions, from which developing countries that are net importers of the mineral in question are exempt, are to be equitably distributed among state parties to the convention through the International Seabed Authority.

The convention also contains a new feature in international law, which is the regime for archipelagic states (such as the PHILIPPINES and INDONESIA, which are made up of a group of closely spaced islands). For those states, the territorial sea is a 12-mi zone extending from a line drawn joining the outermost points of the outermost islands of the group that are in close proximity to each other. The waters between the islands are declared archipelagic waters, where ships of all states enjoy the right of innocent passage. In those waters, States may establish sea lanes and air routes where all ships and aircraft enjoy the right of expeditious and unobstructed passage.

The Convention on the Law of the Sea holds out the promise of an orderly and equitable regime or system to govern all uses of the sea. But it is a club that one must join in order to fully share in the benefits. The convention, like other treaties, creates rights only for those who become parties to it and thereby accept its obligations, except for the provisions that apply to all states because they either merely confirm existing customary law or are becoming customary law. The convention was adopted as a “package deal,” with one aim above all, namely universal participation in the convention. No state can claim that it has achieved quite all it wanted. Yet every state benefits from the provisions of the convention and from the certainty that it has established in international law in relation to the law of the sea. It has defined rights while underscoring the obligations that must be performed in order to benefit from those rights. Any trend toward exercising those rights without complying with the corresponding obligations or toward exercising rights inconsistent with the convention, must be viewed as damaging to the universal regime that the convention establishes.

In the 21st century, the military aspects again became important. Now it is the right of a country’s national defense to board and stop military cargoes to “rogue” nations or for use by terrorists. Coastal zones and CHOKE POINTs were no longer the primary focus of the Law of the Sea.