Lords of Navigation: Grotius, Freitas, and the South China Sea
Image Credit: REUTERS/Erik De Castro



The ornate Tower of Belém, with its faded ivory parapets, still stands proudly above the Tagus River, a monument to a distant era. Built in 1502 to commemorate Vasco da Gama’s expedition to the East Indies, the fortress was the final gateway navigators would pass before entering the sea beyond. Further afield, along the shorelines of Africa and Asia, Portuguese explorers erected stone pillars, padrões, as reminders of home and markings for a new imperial domain. In the early 17th century, the parameters of the Estado da India became the subject of an intense international legal contest, the principles of which are still under dispute.

What the Portuguese discovered in Asia was an active free trading zone involving Arab and Chinese merchants converging on cosmopolitan ports such as Malacca. While the West had been disconnected from the East following the fall of Rome, the open waters of Asia represented the height of global commerce. In his classic study An Introduction to the Law of Nations in the East Indies (1967), Charles H. Alexandrowicz reviewed Asian maritime codes and customs. He found that the high seas, from the Arabian Sea to the edge of the Pacific, were freely navigated and considered as being beyond any sovereign’s control.

Following their arrival in 1498, however, the Portuguese established a new order wherein they claimed a monopoly on trade in the East Indies and sovereignty over the high seas. This exclusivity served national security goals (by undermining the economic resources of Islamic enemies, such as the Ottoman Empire, which threatened Western Christendom) and commercial interests (by preventing market access for European competitors). At the end of the 16th century, the Dutch were on the rise and challenging Portugal’s maritime hegemony in Asia.


Matters came to a head in 1603 when the Dutch East India Company (the “VOC”) seized a Portuguese carrack, the Santa Catarina, near present-day Singapore. The VOC engaged a young and celebrated lawyer, Hugo Grotius, to write a brief explaining that the ship and its valuable cargo had been taken as booty in a just war. Grotius anonymously published Mare Liberum (The Free Sea) (1609), which presented a novel challenge to existing European orthodoxy. Subsequently, Serafim de Freitas, a Portuguese friar on Valladolid’s Faculty of Law in Spain, authored a response, De justo imperio Lusitanorum Asiatico (1626), advocating for jurisdictional rights over the sea.

Grotius’ groundbreaking doctrine of the free sea eventually triumphed and is codified in the United Nations Law of the Sea Convention (UNCLOS). However, Freitas’ views concerning quasi-possession have also proved influential in shaping modern coastal state claims to adjacent waters, zones beyond, and the sea bed itself. As the Permanent Court of Arbitration prepares to issue new precedent concerning maritime claims in the South China Sea, it is worth reviewing the contours of the original debate.

Freedoms of Navigation and Trade

According to Grotius, the freedoms of navigation and trade are natural rights that may not be infringed. Nature has spread its varied gifts – from human capabilities to natural resources – across the globe. As a result, Grotius reasoned that nations are destined to engage in reciprocal relations. Underlying this mutual exchange is open access to each other via the “common water and, and the common air,” as described by the poet Virgil. He observed that the winds and currents of the sea promote travel and trade. In turn, Grotius concluded that the law of nations forbids any actions to undermine these primary, immutable rights. Circumscribing these rights, by forbidding access or hindering navigation, is cause for a just war.

In contrast, Freitas argued that the rights to commerce and navigation do not derive from primary rights under an original, pristine state of nature. Instead, these rights are human creations, corruptible and, therefore, mutable. Given this permissiveness, sovereign nations have the discretion to prevent access to their markets and territory.

Freitas found that Grotius failed to differentiate among three scenarios: (1) innocent passage; (2) passage based on exigency and necessity; and (3) unqualified passage. In the first two instances, the law of nations permits passage and denial could be grounds for a just war. In the case of the third, however, each nation has the sovereign right to refuse trade and access to foreigners, particularly on the basis of self-defense.

Claims to the High Seas 

In the Grotius view, the freedoms of navigation and trade are grounded in the unique character of the high seas. The sea cannot be possessed and remains common by nature. Therefore, the sea cannot be justly or effectually appropriated by discovery, prescription, and custom.

Under the law of nations, the sea has been characterized as the property of no one (res nullius), or a common possession (res communis), or public property (res publica). Regardless of the precise categorization, at its essence, Grotius argued, “the sea is a thing so clearly common to all, that it cannot be the property of any one save God alone.” Nature provided the sea to all of humanity and, therefore, the sea cannot be alienated by any person or nation. Moreover, since the use of the sea is derived from a common right, no private right can be derived from any use of the sea.

Grotius further reasoned that the sea could not and has never been occupied, and all rights of property, including discovery, have arisen from occupation. He also sought to preempt arguments of public utility that underlie natural law. The demarcation of property, for example, prevents indiscriminate use and, thus, exhaustion of resources. In his view, the inexhaustible nature of the sea was such that the freedom of navigation would not impinge on the sea’s common use. As he explained, “But there is not a single person in the world who does not know that a ship sailing through the sea leaves behind it no more legal rights than it does a track.”

In addition, the Portuguese cannot claim to have first discovered and occupied the sea. Grotius argued that if first navigation were the test, then the entire sea would be exclusively possessed because there is no part of the sea that had not been previously navigated. Moreover, he found it ridiculous to assume that the peoples of Asia remained ignorant of the sea adjacent their coasts prior to Portugal’s arrival.

Grotius considered claims to the seas based on prescription and custom as being undermined by the same fatal flaw: The sea is not susceptible to possession or quasi-possession and, therefore, cannot be anyone’s property. The imprescriptible nature and commonality of the sea does not change even with the passage of time, through tacit consent, or by the practice of many states.

Even if prescription were possible, the conditions required present an extremely high bar: the claimant must be in possession of the sea since time immemorial; during this time, no other party can exercise the same right of possession unless with the consent of the claimant or clandestinely; all other parties must have been prevented from using the possession without exception; and this later prohibition must be common knowledge and executed without objection. Grotius found Portugal’s case insufficient. For example, within 100 years of Portuguese arrival, the Dutch, English and French, sometimes by force of arms, had accessed and navigated the seas of the East Indies and, therefore, usurped any potential prescriptive claim.

Grotius acknowledged that if any part of the sea were susceptible to occupation, then that occupation could be recognized, but only so far as such occupation would not affect the sea’s common use. Grotius also distinguished between the high sea and coastal waters, bays, and gulfs. The test was the coastal state’s ability to physically defend and effectively exercise control over the waters. In the case of the Adriatic Sea, for example, the Venetians could plausibly exercise control from their long coast line, but the same could not be said of the Portuguese and the expansive seas of the East Indies. Freitas would attempt to exploit this concession.

In response to Mare Liberum, Freitas developed a concept of “quasi-possession” to explain the lawful acquisition of the sea under the law of nations.

Freitas first challenged Grotius’ interpretation of Roman law and found that although the sea was considered common property it still fell under the emperor’s dominion. Similar to John Selden and William Welwod, he explained that natural law also promotes the exclusive possession of the sea because the sea and its resources are, in fact, exhaustible and damaged through indiscriminate use.

Seizing Grotius’ admission on effective control, Freitas argued that the immensity of the sea has never been a complete obstacle to partial occupation, with the critical constraint being the Sovereign’s actual power to exercise dominion. In this regard, the surface of the sea is distinguishable from the sea bed. Freitas cited the historical precedent of nations such as Venice claiming exclusive rights over the Adriatic. Even in Asia, the free see had been limited by claims of coastal states to power over navigation and fishing rights in the waters adjacent to their territories. As Freitas states: “Though we do not admit Sovereignty over the sea, its protection and jurisdiction over it may belong to the Sovereign.”

If the sea can be quasi-possessed by acts of navigation and placed under the jurisdiction of the Sovereign, then the sea can acquired by discovery, prescription, especially immemorial, or custom, in accordance with the law of nations. Freitas maintained that the basis for these claims is the actual physical control and intention to hold the property exclusively. This intention may be demonstrated through actions (prohibiting foreign use), by express declaration, or by a superior grant of title.

Freitas observed that the Portuguese had availed themselves of each method. First, through the system of cartazes (safe conduct), Portugal sought to effectuate their quasi-possession over navigation rights. Second, King Manuel I of Portugal sufficiently expressed his will to possess and control the sea routes of the East Indies, through his title “Lord of Conquest, Navigation, and Commerce of Ethiopia, Arabia, Persia, and India, etc.” Third, Portugal had been granted superior title over this vast domain through successive papal donation. According to Freitas, the Portuguese claim of immemorial prescription or custom began with the pontifical grant of Martin V (1417) and this title was reinforced by the actual occupation of the seas by Portuguese navigators like Vasco da Gama.

South China Sea

Today, China and the United States, like the Portuguese and Dutch four hundred years ago, are sparring over Asia’s maritime domains.

China has asserted “indisputable sovereignty” over the South China Sea consistent with a map depicting a nine-dash boundary encompassing nearly the entirety of the sea, well-beyond any mainland coastline. What is the basis for this claim? Beijing’s assertions of discovery, prescription, and custom would be familiar to Freitas:

“Chinese activities in the South China Sea date back to over 2,000 years ago. China was the first country to discover, name, explore and exploit the resources of the South China Sea Islands and the first to continuously exercise sovereign powers over them.”

Moreover, for China, the state of nature is not ideal or protected, but mutable and corruptible through effective control. Beijing even claims an ability to manufacture new rights from land reclaimed from the sea.

The United States, echoing the Dutch humanist, answers that that the high seas are open to all states and not subject to claims of sovereignty by any nation. Nature is the ideal; artificial structures do not create sovereign privileges. Even if historic title over the South China Sea was available, Washington asserts that this claim must be supported by: (1) an open, notorious, and effective exercise of authority; (2) continuous exercise of that authority; and (3) acquiescence by foreign states in the exercise of that authority. This is a high bar to clear for a Chinese claim spanning two millennia, particularly when considering that during the self-described “Century of Humiliation” Beijing did not exercise effective authority over its mainland, not to mention purported maritime domains.

The debate between Grotius and Freitas reminds us that the development of maritime principles has not followed a linear progression. Each side has espoused principle and accepted political expediency. What is inarguable is that matters have again come to a head. The disputes of the South China Sea represent a significant challenge to the existing maritime order. The international community must now decide whether UNCLOS and the free sea have become dead letters, like stonewashed markers along the coast, memorials from a different epoch.

Roncevert Ganan Almond is a partner at The Wicks Group, based in Washington, D.C. He is author of an article on East Asia’s maritime disputes in the current issue of the Harvard National Security Journal and has served as an advisor to government authorities in Asia, Europe, the Middle East, Africa, and Latin America on issues of international law. The views expressed here are strictly his own.

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