The international law of the sea is governed by three principles: the principle of freedom, the principle of sovereignty and the principle of the common heritage of mankind. Traditionally the law of the sea has been dominated by the principle of freedom and the principle of sovereignty. The French jurist R.-J. Dupuy summarized the essence of the law as follows:
The sea has always been lashed by two major contrary winds: the wind from the high seas towards the land is the wind of freedom; the wind from the land toward the high seas is the bearer of sovereignties. The law of the sea has always been in the middle between these conflicting forces.
The principle of freedom aims to ensure the freedom of various uses of the oceans, such as navigation, overflight, laying submarine cables and pipelines, construction of artificial islands, fishing and marine scientific research. Historically the principle of freedom may primarily be thought of as aiming to ensure the freedom of navigation in order to advance trade and commerce overseas. At the start of the era of European expansion in global navigation, the papal bull Inter Caetera of 4 May 1493 issued by Pope Alexander VI, granted Spain and Portugal all newly discovered and to-be-discovered lands, that were divided into two with a straight line – towards the west of it unto Spain and the east, Portugal.
However, this was not welcomed by other maritime nations. In this context, mention should be made of the Mare Liberum by the Dutch jurist Hugo Grotius. In February 1603, a Dutch squadron captured Sta. Catharina, a Portuguese galleon, in the straits of Singapore, and brought the vessel to Amsterdam. When the vessel’s extremely rich contents were sold as prize, controversy arose with regard to the legality of the capture. Grotius was asked to prepare an opinion on this subject at the request of the Dutch East India Company. The treatise written by Grotius was later known as De Jure Praedae Commentarius, which was not fully published until 1868, with only the twelfth chapter published anonymously in 1609 as Mare Liberum. In this chapter, Grotius upheld the freedom of navigation and trade to the East Indies. This episode would seem to demonstrate that the freedom of the seas was essentially characterised by the economic and political interests of maritime powers.
Grotius’ argument met with criticism from various writers, such as Scottish academic William Welwood, English lawyer and scholar John Selden, Portuguese friar Seraphin de Freitas, and others, who claimed sovereignty over coastal seas for their State’s interests. The debate lasted throughout the seventeenth century, but the principle of freedom of the seas has been consolidated through State practice. Indeed, freedom of navigation was essential for maritime powers in order to secure their trade; and when European rivalry developed into global conflicts in the eighteenth century, overseas naval bases provided strategic interests, especially for Great Britain, the leading maritime power of the time. During the nineteenth century, freedom of the seas was consolidated by the Pax Britannica. Overall the freedom of navigation contributed to maritime powers securing their economic interests and maritime networks, and expanding their political or military influence over their overseas colonies.
source: The International Law of the Sea, Yoshifumi Tanaka