Writing for The Diplomat, Associate Editor Prashanth Parameswaran notes an incident which occurred in February 1603, in which ships commanded by Jacob van Heemskerk of the Dutch East India Company seized the Santa Catarina, a Portuguese merchant ship, without explicit authorization to do so. To defend the seizure, the Dutch hired a 26-year old lawyer named Hugo Grotius, who claimed that it was a legitimate challenge to Portugal’s monopoly on commerce with Asia. The incident happened off Singapore’s upper east coast, near Changi, where the Santa Catarina was anchored after sailing from Macau to Malacca.
Grotius’ opinion would subsequently be published in Mare Liberum (The Free Sea) and De Jure Praedae (On the Law of Prize and Booty). Grotius’ arguments about the freedom of the seas, and just war, would be folded into his corporate works that became the foundation of the modern law of nations (not to be confused simply with contemporary international law, by the way, although the former fed into the latter).
Grotius’ views were by no means met with universal approval: John Selden argued to the contrary in Mare Clausum (Enclosed Sea, 1635). As Parameswaran points out, as does this article in the Straits Times, such arguments continue to inform the current discussions on territorial and maritime disputes in the South China Sea, such as the legitimacy of China’s “nine-dashed lines” map.