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Freedom of navigation

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Based on Wikipedia: Freedom of navigation

In 1609, a young Dutch jurist named Hugo Grotius published a pamphlet that would fundamentally alter the geopolitical architecture of the planet. Titled Mare Liberum, or "The Free Sea," it was not merely a legal argument but a declaration of war against the idea that the ocean could be owned. At the time, the great powers of Spain and Portugal, bolstered by papal decrees and naval might, treated the Atlantic and Indian Oceans as private fiefdoms, closing them off to rival merchants and consolidating their empires in the New World and Asia. Grotius, writing to defend the Dutch East India Company's right to trade in the East Indies, articulated a radical premise: the sea is by its nature a common resource, incapable of being possessed, and therefore no sovereign state has the right to deny passage to ships flying the flag of another nation. This was the birth of the modern concept of Freedom of Navigation (FON), a principle that has since evolved from a revolutionary manifesto into the bedrock of Article 87(1)a of the 1982 United Nations Convention on the Law of the Sea.

Today, this concept feels as natural as breathing. We assume that a cargo ship flying the Panamanian flag can traverse the South China Sea or the Strait of Hormuz without asking permission from Beijing or Tehran. We assume that international waters are a global commons where the only law is the law of the sea itself. Yet, this stability is a recent historical invention, the result of centuries of brutal conflict, shifting naval hegemonies, and a philosophical struggle over whether the ocean is land to be conquered or a highway to be shared. To understand the fragility and power of the current maritime order, one must look back at the chaotic centuries where the very idea of "free seas" was contested, where neutral ships were hunted, and where the right to navigate was a privilege granted by the strongest gun, not a right guaranteed by law.

The Ancient Paradox and the Consolato Rule

Long before Grotius penned his famous tract, the theoretical framework of the seas was a tangled web of contradiction. In both Roman law and Islamic law, the notion of a "commonality of the seas" was firmly established. The Roman jurists recognized the sea as res communis, a thing common to all, and Islamic legal traditions similarly viewed the ocean as a shared domain where no single power could claim exclusive dominion. However, theory and practice were often miles apart. In reality, Romans, Europeans, and Muslim states frequently claimed jurisdiction over vast stretches of the sea, treating coastal waters as extensions of their territory and often extending that reach far into the open ocean.

It was not until the early modern period that international maritime law began to coalesce into something resembling a coherent system. Until then, the rules of the sea were governed by a patchwork of local customs that differed wildly across legal systems. These customs were rarely codified on a global scale, though exceptions existed. A prime example is the 14th-century Consulate of the Sea (known in Spanish as Consulado del mar and in Italian as Consolato del mare), a comprehensive code of maritime law developed in the Crown of Aragon. This document, along with similar codes of the era, became the standard for prize courts—specialized tribunals that adjudicated cases regarding the capture of goods on the high seas by privateers and navies.

The Consolato customs established a framework that was starkly different from the "free seas" ideal that would emerge later. Under these rules, the concept of neutral shipping was not inviolable. The prevailing maxim was simple and brutal: "enemy goods can be captured on neutral ships and neutral goods are free on board enemy's ships." This became known as the consolato rule. It meant that in times of war, a navy was free to attack and seize ships of any nation on the open seas. If a neutral ship was found carrying goods belonging to an enemy state, those goods could be confiscated, even if the ship itself was neutral. Conversely, if an enemy ship was carrying neutral goods, those specific goods were to be left untouched, though the ship itself was a lawful prize.

This legal custom created a world where the flag of a merchant vessel offered no guarantee of safety. Major naval powers like England (later Great Britain), France, and Spain long observed this rule because it served their strategic interests. As the dominant maritime powers, they possessed the largest navies and the most aggressive privateering fleets. The consolato rule gave them a powerful weapon: the ability to strangle an enemy's economy by intercepting neutral vessels carrying enemy cargo. It turned the high seas into a battlefield where neutrality was a fragile shield, easily pierced by the assertion of belligerent rights.

The Clash of Ideologies: Mare Clausum vs. Mare Liberum

As European powers began to stretch their reach beyond their traditional waterways, venturing into the New World, across Africa, and into the complex trade networks of Asia, the old customs began to fracture. Two distinct schools of thought emerged in the 17th century, representing a fundamental clash between the desire for exclusive control and the necessity of open trade.

The first school championed the concept of mare clausum, or "closed sea." This theory, most famously promoted by the English jurist John Selden, argued that states could limit or even completely close off seas and maritime areas to the access of foreign ships. Selden's logic was an extension of terrestrial sovereignty: just as a state could own land and exclude others, it could own the sea and deny passage. Other notable supporters of this restrictive view included John Burroughs and William Welwod. In the larger geopolitical context, mare clausum was the ideology of choice for the major colonial powers of the day, particularly Spain and Portugal. As these empires expanded their territories and sought to consolidate control over their new colonies, they wished to monopolize access to the trade routes and resources that led to them. By literally closing off the seas using their naval muscle, they aimed to profit handsomely from the growing maritime trade, ensuring that no rival power could siphon off the wealth of their empires.

Opposing this vision was the Dutch Republic, the dominant European trade carrier of the 17th century. The Dutch championed a radically different rule: mare liberum, or "free seas." This concept was summarized by the maxim "a free ship [makes] free goods." This meant that even enemy goods, with the exception of contraband, were inviolate when transported in neutral bottoms (hulls). A neutral ship was to be considered off-limits for attack on the high seas, regardless of the cargo it carried. For the Dutch Republic, this was not a matter of abstract philosophy but a matter of existential survival. As a small nation with a massive merchant fleet but a relatively small population, the Dutch economy depended entirely on their ability to transport goods for everyone. They needed the seas to be open to secure the safety and viability of their extensive trade network.

The intellectual architect of this movement was Hugo Grotius. A Dutch jurist and a founding father of international law, Grotius advocated for a shift in maritime norms that would make the high seas free for transport and shipping, regardless of the country of origin of the ship. This represented not only a change in law but a fundamental shift in the perception of the maritime realm. Grotius argued that the sea, unlike land, was a shared resource that could not be owned. Behind this concept lay a liberal view of sovereign equality, wherein all states possessed equal access to the high seas, and a vision of an interdependent world connected by the ocean. As the naval dominance of Spain and Portugal began to wane and international trade exploded, Grotius's concept of mare liberum gradually came to be accepted as the governing custom of sovereignty at sea.

The Treaty Web and the Rise of Neutral Rights

The transition from mare clausum to mare liberum was not immediate. It was forged through a series of bilateral treaties that slowly embedded the principle of freedom of navigation into the fabric of international relations. The earliest example of such a treaty was concluded in 1609 between King Henry IV of France and the Ottoman Porte, followed in 1612 by a similar agreement between the Porte and the Dutch Republic. These agreements signaled a shift in the diplomatic landscape, where the right to navigate was increasingly recognized as a standard privilege rather than a concession.

The pivotal moment came with the end of the Eighty Years' War between Spain and the Dutch Republic. During this conflict, Spain had fiercely defended its claim of sovereignty over the oceans against the Dutch claim of "freedom of the high seas," a concept Grotius had articulated in Mare Liberum. When the war finally concluded, the two powers signed a treaty of commerce in which the principle of "free ship, free goods" was enshrined. This was a monumental victory for the Dutch and a significant step toward the codification of freedom of navigation.

The Dutch Republic subsequently leveraged this victory to conclude bilateral treaties with most other European countries, spreading the "free ship, free goods" principle across the continent. However, the path was not always peaceful. The Dutch sometimes resorted to the use of force to obtain these concessions. Notable instances include the Treaty of Breda in 1667 and the Treaty of Westminster in 1674, where Dutch naval power compelled England to accept the principle. England, however, remained a holdout. For decades, Great Britain held fast to the consolato rule in its relations with other countries, as did France, until France relented in 1744 and extended the privilege to the neutral Dutch.

Through these diplomatic and military efforts, the Dutch eventually established a vast web of bilateral treaties that extended the privilege of "freedom of navigation" to their ships throughout much of Europe. During the numerous 18th-century European wars, the Dutch Republic remained neutral, serving all belligerents with their shipping services. This strategy allowed them to become the primary carriers of global trade, profiting from the conflicts of others while their own merchant fleets sailed under the protection of their treaties.

The British Reaction and the Crisis of the American Revolution

Great Britain, in particular, chafed under this arrangement. As the dominant naval power of the 18th century, Britain relied on its ability to enforce blockades and intercept enemy supplies to win wars. The Dutch privilege of "free ship, free goods" undermined the effectiveness of these blockades, allowing neutral vessels to carry enemy goods to British adversaries with impunity. Matters came to a head during the American Revolutionary War. The Dutch, shielded by the 1674 Anglo-Dutch treaty, continued to supply both the American colonists and the French, their traditional rivals. The British, frustrated by this erosion of their naval supremacy, made extensive use of their "right of search" to detain Dutch merchant ships.

The tension erupted into the affair of Fielding and Bylandt, where a Royal Navy squadron detained a Dutch merchant convoy. This incident nearly sparked a war and highlighted the fragility of the existing treaty system. Soon afterward, the North ministry in London abrogated the 1674 treaty, a move that threatened to dismantle the "free ship, free goods" doctrine entirely. However, the principle had found a new and powerful champion in the north.

Empress Catherine II of Russia had taken up the torch. In March 1780, she published a manifesto claiming the "free ship, free goods" principle as a fundamental right of neutral states. To defend this principle, she formed the First League of Armed Neutrality. The Dutch adhered to the League at the end of the year, a move that directly sparked the Fourth Anglo-Dutch War. The principles from Catherine's manifesto were soon adhered to by the members of the League, as well as by France, Spain, and the new American Republic. Although these nations were belligerents and could not technically become members of the League, they accepted the principles as valid international norms.

The 19th Century and the Codification of Law

Despite the diplomatic successes of the late 18th century, the principle of "free ship, free goods" was not universally cemented. As the 19th century dawned, the practice of both sides in the French Revolutionary Wars often overturned the principle. In the jurisprudence of American courts during the early 19th century, the consolato principle was universally applied in cases not covered by specific treaties. The courts ruled that without a treaty explicitly guaranteeing neutrality, the old rules of capture applied.

However, the United States government made it a steadfast practice to enshrine the "free ship, free goods" principle in the treaties of amity and commerce it concluded with other countries. This started with the 1778 treaty with France and the 1782 treaty with the Dutch Republic. In other words, the US recognized that while customary international law might be fickle and subject to the whims of war, treaty law provided a more reliable shield for its merchants.

The struggle between the consolato rule and the mare liberum ideal continued to shape international relations throughout the 19th century. The concept of freedom of navigation evolved from a revolutionary Dutch slogan into a cornerstone of international law, but it required the constant reinforcement of treaties and the shifting balance of power to survive. The eventual codification of these principles in the 1982 United Nations Convention on the Law of the Sea (UNCLOS) marked the culmination of this centuries-long journey. Article 87(1)a of UNCLOS explicitly states that the high seas are open to all states, whether coastal or land-locked, and that freedom of the high seas comprises, inter alia, freedom of navigation.

The Modern Imperative

Today, the principle of Freedom of Navigation is more than a legal technicality; it is the lifeblood of the global economy. Over 90% of global trade by volume is carried by sea. The Strait of Hormuz, the Malacca Strait, the Suez Canal, and the Panama Canal are the arteries through which the world's energy and goods flow. Any attempt to close these waterways, or to assert exclusive sovereignty over them, threatens to sever the economic connections that sustain modern civilization.

The historical struggle between mare clausum and mare liberum is not merely a relic of the past. It is a recurring theme in contemporary geopolitics. When nations attempt to claim exclusive economic zones that extend far beyond the 12-nautical-mile territorial limit, or when they restrict the passage of foreign warships through international straits, they are echoing the arguments of John Selden and the Spanish Empire. Conversely, when nations conduct Freedom of Navigation Operations (FONOPs) to challenge excessive maritime claims, they are acting as the modern successors to Hugo Grotius and Catherine the Great.

The lesson of history is clear: the freedom of the seas is not a natural state of affairs. It is a constructed order, fragile and contested, that requires constant vigilance and the willingness to defend it. The shift from a world where the sea was a private domain to be owned to a world where it is a shared resource to be navigated was one of the most significant transformations in human history. It allowed for the explosion of global trade, the rise of interconnected civilizations, and the development of a legal framework that governs the interaction of nations on a planetary scale.

As we look to the future, the principles established by Grotius and refined over centuries remain as relevant as ever. The ocean continues to be a shared resource, a space where the sovereign equality of states must be respected. The challenges may have changed—from the privateers of the 17th century to the cyber-attacks and drone swarms of the 21st—but the fundamental imperative remains the same: the seas must remain free. For as long as trade flows and nations interact, the freedom of navigation will remain the silent engine of the global order, a testament to the power of an idea that the ocean belongs to no one, and therefore, to everyone.

The journey from the Consulate of the Sea to the United Nations Convention on the Law of the Sea is a story of human ingenuity and conflict. It is a story of how a group of merchants and jurists managed to convince the world that the ocean was not a place to be conquered, but a highway to be shared. In doing so, they unlocked the potential for a global economy that has lifted billions out of poverty and connected cultures in ways previously unimaginable. The price of this freedom has been paid in blood and gold, in wars fought over the right to sail, but the result is a world that is richer, more connected, and more peaceful because the seas remain open.