Unclos: ‘Mare Liberum’ or ‘Mare Clausum’? | Inquirer Opinion
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Unclos: ‘Mare Liberum’ or ‘Mare Clausum’?

Over the years, the laws of the sea have tended to ebb and flow with the changing political and economic tides. During the Roman era, the concept of Mare Nostrum governed states’ claims to the sea. Under the Mare Nostrum regime, Rome extended its sovereignty outwardly to encompass the breadth of the Mediterranean Sea, subjecting it to Rome’s internal laws. Norway and England followed suit, claiming the entire North Sea and the English Channel, respectively, as their exclusive territories.

In the 17th century, John Selden published his work, “Mare Clausum sen de Domino Maris Libri Duo,” which translates to “closed seas.” As its name suggests, the Mare Clausum regime accords use and exploitation only to states with naval capabilities, particularly England. Selden argued that since naval states guarded against maritime perils such as piracy, naval states should rightfully exercise exclusive jurisdiction over the sea. Due to England’s continuing naval prowess, Mare Clausum remained in force for the next 200 years.


But earlier in the 17th century, Hugo Grotius published his seminal work, “Mare Liberum.” Under this view, the sea should be open to all states for exploration and trade, irrespective of naval capabilities. Mare Liberum revolved around two key principles: first, that “the High Seas were laissez-faire domains to be used by all nations,” and second, that no state could claim these as their own. Although published earlier than Mare Clausum, Mare Liberum did not gain traction until much later when the rest of Europe began to engage in trade. Due in part to an increase in international commerce, Mare Liberum continues to govern the high seas.

Despite the popularity of Mare Liberum, sovereignty over territorial waters nevertheless remained an important concern. States continued to recognize coastal states’ right to protect waters extending from their coasts, despite widespread acceptance of the freedom of the high seas. Traditionally, this protection extended only three miles from the shore, since this was the maximum distance that could be reached by a cannon. The current laws governing the sea evolved from the struggle between those espousing the freedom of the seas and those championing sovereign dominion over them.


The changes ushered in by the 20th century served to strengthen states’ territorial claims over the sea. Improvements in fishing techniques and the discovery of offshore oil resources drove states to stake claims over larger breadths of sea. In 1945, US President Harry Truman asserted US jurisdiction over the natural resources of the subsoil and seabed of the continental shelf beyond its territorial sea. On the same day, he established a “fisheries conservation zone” extending beyond the US territorial sea. Significantly, many other states followed suit, extending their authority beyond their territorial sea.

In 1982, the third United Nations conference on the law of the sea finally concluded. The resulting UN Convention on the Law of the Sea (Unclos) served to strengthen sovereignty over the seas, as it extended states’ territorial sea to 12 nautical miles and recognized their exclusive jurisdiction over their internal waters. Beyond the territorial sea, coastal states were extended additional rights 24 nautical miles and 200 nautical miles outward from their baselines, respectively, in their contiguous zone and exclusive economic zone. Further, waters running between islands of an archipelagic state are now subject to its jurisdiction.

With the addition of the contiguous zone and exclusive economic zone, the area of the high seas has begun to dwindle. Nevertheless, the Unclos demonstrates continued respect for the freedom of the high seas. In fact, the Unclos expressly provides that the high seas are open to all states, and that no state may subject any part of the high seas to its sovereignty. Consequently, state parties cannot unilaterally extend their sovereignty beyond the areas delineated in the Unclos, as waters that lie beyond the exclusive economic zone are high seas. The right of all states to fish in the high seas is likewise preserved in the Unclos.

Even the provisions that extend sovereign rights over the seas do not completely abrogate the freedom of the seas. Although the Unclos grants each coastal state rights over their contiguous zone and exclusive economic zone, these rights do not confer absolute dominion over these areas. The coastal states’ rights over the contiguous zone encompass only preventive measures against infringement of its customs, fiscal, immigration or sanitary laws. Similarly, coastal states are merely accorded exploration, exploitation, conservation and management rights over their exclusive economic zones. Significantly, the Unclos encourages coastal states to allow other states to share in the resources of its exclusive economic zone. While archipelagic states are now sovereign over the waters between their islands, the Unclos mandates free passage between such waters, as a concession for granting archipelagic states such rights.

The freedom of the seas was premised on the notion that the sea and all the resources that lie beneath it are infinite and immeasurable. Time has proven that neither of these is true. Consequently, the current regime which has increased sovereign rights at the expense of the freedom of the high seas will likely continue to govern until the dictates of security, politics or economics require otherwise. (Research contributions of Atty. Gaston Perez de Tagle are gratefully acknowledged.)

Ricardo J. Romulo is a senior partner at Romulo Mabanta Buenaventura Sayoc & De Los Angeles.

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TAGS: Mare Clausum, Mare Liberum, Mare Nostrum, Maritime Dispute, territory, Unclos
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