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This long-contentious question remains hotly disputed today

The Dutch jurist Hugo Grotius is most often cited for his contributions to the development of international laws of war. Before he published his magnum opus, On the Law of War and Peace, in 1625, however, he wrote a smaller work titled Mare Liberum (The Free Sea). It was not much more than a chapter excerpted from his study of the 17th-­century practice of prize taking in naval conflict, but the influence of Grotius’s short essay was to survive far beyond his lifetime. It was, as the U.S. Naval War College describes it, nothing less than “the first formal statement of freedom of the seas as a general principle of international law.” 

It was a simple enough proposition for the world’s seagoing nations to agree, at least in theory, that unimpeded navigation of the high seas was to the benefit of all concerned. In practice, however, the question of where a nation’s territorial waters and maritime sovereignty end and the high seas begin was a contentious point that remains hotly disputed today.

An early attempt at resolving the question was advanced by another Dutch jurist, Cornelius van Bynkers-hoek, who postulated that “the dominion of land ends where the power of arms ends,” which was understood to mean “so far as cannon balls are projected.” That, of course, was imprecise, so in 1782 an Italian scholar pinned the distance at one sea league. Since Thomas Jefferson, as U.S. secretary of state, had determined that one sea league was indeed the maximum range of cannon shot, the United States accepted one sea league, or three miles, as the reach of its territorial waters. The British government concurred, but its insistence on being allowed to engage in “hovering acts,” by which ships of the Royal Navy were empowered to overhaul and board vessels outside Britain’s territorial waters on suspicion of criminal activity, contradicted that limitation until it discontinued the practice in the late 1800s.

The Court of International Justice in The Hague meets in 1948 to consider Britain’s dispute with Albania over the Corfu incident. (Kurt Hulton/Getty Images)

The theory of a nation’s right to defend its territorial waters was problematic when long-established sea lanes fell within the lines of new territorial claims on maritime charts. Certain narrow passages between mainland and islands such as the Vilkitsky Straits in the Arctic Circle or the Corfu Channel off the Albania coast or constricted waters like the Gulf of Aqaba east of the Sinai Peninsula have been scenes of international dispute and outright conflict when one nation contests the passage of another nation’s ships through what it regards as its territorial waters. In a series of conferences in the 20th century, as more and more nations declared a 12-mile reach into open seas, participants fiercely debated the limit of national sovereignty in coastal waters.

The 1958 Geneva Convention on the Law of the Sea established limits for territorial waters but also recognized that national sovereignty was far from absolute in those seas. Rather, it held, territorial waters “are subject to limitations imposed by the community of nations by means of international law.” One of those limitations is the doctrine of innocent passage.

The concept of innocent passage holds that ships of all nations are free to sail through seas claimed as territorial waters by any other nation so long as the vessels meet certain conditions. It is not a reciprocal policy because international law and custom insist that ships of unfriendly nations are just as free to transit those lanes as are ships of allied or friendly states. Two types of vessels, however, continue to generate argument and conflict: fishing boats, because of their economic importance, and naval warships, for reasons of national security. 

British sailors drag ashore one of the mines in the Corfu Channel. (Imperial War Museums)

The Geneva Convention defined “passage” as “navigation through the territorial sea for the purpose either of traversing that sea without entering internal waters, or of proceeding to internal waters, or of making for the high seas from internal waters.” It is an important distinction, because before then it was widely held that a ship in passage, just like a ship in port, was under the coastal nation’s authority. Passage was thereafter determined to be “innocent” as long as a ship’s transit was “not prejudicial to the peace, good order or security of the coastal State,” as the 1982 United Nations Convention on the Law of the Sea termed it.

The United States interpreted this language as pertaining only to military security, but India and other nations insisted that it encompassed far more. Britain, voicing the most widely held view, maintained that the manner in which the passage was conducted, rather than the transit itself, should determine whether a ship’s passage was innocent. Did the vessel have its guns raised, for example, or fail to respond to signals and communications from the coastal nation? Language discussing the unique capabilities of submarines was also included in the Convention’s final draft, which required them “to navigate on the surface and to show their flag,” thereby announcing their peaceful intentions.

An incident in the North Corfu Channel in 1946 was one of the first tests of this doctrine after World War II. The British destroyers Saumarez and Volage, sailing through the channel, struck mines in an uncharted minefield moored in Albanian waters. The Royal Navy, without seeking a diplomatic resolution, proceeded to clear the waters of mines. Albania disavowed any knowledge of the minefield and insisted in the International Court of Justice that Britain had violated its sovereignty by sending warships through waters that were a secondary passage and not an essential shipping lane between high seas. 

The court, holding that the strait connected two portions of the high seas that had been established as an area of international maritime navigation, rejected the Albanian argument that a body of water must be a “necessary route” to qualify for innocent passage. “The North Corfu Channel,” it ruled, “should be considered as falling under the category of international maritime thoroughfares, through which passage cannot be prohibited in time of peace by a coastal state.” In fact, Britain’s decision to send the Saumarez and Volage through the strait was a strategic one, intended to test Albania after an incident earlier that year in which Albanian coastal batteries had fired on British vessels in the channel. In the court’s view, the fact that the British ships sailed with their guns in stowage positions, not trained on the Albanian shore, was enough to indicate that their passage was innocent. What the court decided was not so innocent, however, was Britain’s decision to clear the minefield without first obtaining Albania’s permission—a violation of Albanian sovereignty. Nonetheless, the court did not hold the British government liable for any damages, ruling that Albania had failed to warn ships of other nations of the navigational hazard in its waters.

The ability of warships to claim innocent passage continued to bedevil international jurists after the Corfu Channel incident, and the matter took on greater urgency as the Cold War heightened tension between the nations of the Warsaw Pact and NATO, and repeated Middle Eastern conflicts threatened international shipping in the waters between Africa and Arabia. The Geneva Convention attempted to clarify matters by adopting language requiring warships “to comply with the regulations of the coastal state.” In other words, if a naval vessel violated the coastal state’s demand for compliance, the ship could be ordered to depart the territorial waters immediately. The thorny question, of course, was how one nation could force another nation’s ships to leave its waters, should they refuse to comply, without the situation deteriorating to an exchange of gunfire?

This issue was further complicated when the waters in dispute could be classified as a “closed sea,” or internal water, which was exactly what Egypt claimed when in 1967 it closed the Gulf of Aqaba to all ships “carrying strategic cargo”—and specifically all Israeli-flagged vessels. Britain and the United States, the world’s foremost maritime nations, immediately protested this action in the Security Council of the United Nations. Israel claimed the right of innocent passage on account of its possession of Elath, an ancient settlement at the northern tip of the gulf. The United Arab Republic argued that this was not a legitimate territorial claim since the town had come into Israel’s possession only after the 1949 Egypt-Israel Armistice, and it insisted that territory acquired in war could only be converted to sovereignty if a state of war was resolved by a peace treaty, which was notably lacking in the Arab-Israeli conflict. The dispute ended without any real resolution when both Egypt and Saudi Arabia extended their claimed territorial waters to 12 miles, effectively

From top: An Israeli navy frigate (in background) sails through the Gulf of Aqaba, which Egypt would later close to Israeli-flagged vessels, in 1956; the Soviet frigate Bezzavetny rams the U.S. Navy cruiser Yorktown in 1988. (From top: Associated Press; U.S. Navy)

eliminating any free water in the gulf, but at the same time pledged to allow “free and innocent passage according to international law.”

In 1988 a dispute over U.S. claims to innocent passage in the Black Sea resulted in an incident between American ships and Soviet naval frigates. The U.S. government insisted that innocent passage was not limited to designated sea lanes, in contradiction to the Soviet position, which held that warships were never entitled to innocent passage within its territorial waters. The dispute was so entrenched that the English and Russian-language versions of the U.N. Convention on the Law of the Sea, Article 22, Paragraph 1, interpreted the restrictions differently. The Soviet version allowed the coastal state to restrict innocent passage whenever the USSR decided that a need existed; the American version contained no such restrictions.

The issue between the two nations continued to mount after the United States declared in 1983 that it would uphold “the rights and freedoms of navigation and overflight guaranteed to all nations under international law.” As a result, for several years American naval vessels regularly transited the straits between the Black Sea and the Mediterranean to enforce the U.S. interpretation of innocent passage for warships, particularly in “contested waters such as the Bosporus and Dardanelles.” The USSR recognized no right of innocent passage anywhere in the Black Sea and regarded the U.S. naval activity in its “closed sea” as military provocation. The Soviet Union was not about to start a shooting war over these incursions, but in 1986 it decided to try other means of driving American ships out of its territorial waters.

On February 12, 1988, the cruiser USS Yorktown, accompanied by the destroyer USS Caron, sailed within 10 miles of the Soviet coastline. The Soviet frigates Bezzavetny and SKR-6 sortied to contest the intrusion. As the American vessels passed through Soviet waters, the Caron received a radio message declaring that “Soviet ships have orders to prevent violation of territorial waters, extreme measure is to strike your ship with one of ours.” Caron replied: “I am engaged in innocent passage consistent with international law.” Moments later, SKR-6 turned into Caron’s path and collided with its port side. Yorktown reported receiving a similar warning before Bezzavetny bumped it. Being larger and of greater displacement than the Soviet vessels, the U.S. ships were able to maintain their intended course and two hours later sailed out of the USSR’s territorial waters, shadowed by their slightly damaged Soviet counterparts.

The incident was in keeping with the U.S. interpretation of international laws on innocent passage, with one notable exception. When Caron passed into Soviet territorial waters, its main armament was oriented toward the Soviet coastline, a detail that could be understood as contrary to acceptable conduct while navigating an innocent passage. Both governments subsequently issued diplomatic protests over the other side’s actions in the confrontation, and both remained committed to their respective interpretations of the law.

Clockwise from left: China’s controversial reclamation projects in the South China Sea include a manmade road and construction yard in the Gulf of Tonkin near Quinzhou, the Yangshan Deepwater Port for container ships in Hangzhou Bay south of Shanghai, and an artificial developmeant above the Subi Reef in the Spratly Islands. (Clockwise from left: Qin Ningzhen/Alamy Stock Photo; YHBEST1; Bullit Marquez/Associated Press)

More recently, China’s large-scale reclamation projects in the South China Sea, which have converted submerged reefs into completely new land features, have renewed international and military disputes over the rights and limitations of innocent passage. The Third U.N. Conference on the Law of the Sea, which came into force in 1994, classified such constructions as being on the “sea bed” and thus in international waters regardless of who built them. Under international law, artificial features cannot extend territorial waters. Nonetheless, China continues to insist that it has “the right to engage in monitoring in the relevant air space and waters to protect the country’s sovereignty.”

This was precisely the problem recognized by a U.S. Naval War College study in 1980, which warned that “the community of nations will be subject to the arbitrary denial of passage by states which consider, subjectively, only their own parochial interests.” It was a prescient prediction, because the doctrine of innocent passage continues to be tested throughout the world’s seas. MHQ

John A. Haymond is the author of Soldiers: A Global History of the Fighting Man, 1800–1945 (Stackpole Books, 2018) and The Infamous Dakota War Trials of 1862: Revenge, Military Law, and the Judgment of History (McFarland, 2016).