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Max Planck Encyclopedia of Public International Law [MPEPIL]

Ships, Diverting and Ordering into Port

John Paul Jones

From: Oxford Public International Law (http://opil.ouplaw.com). (c) Oxford University Press, 2015. All Rights Reserved. Subscriber: null; date: 15 November 2019

Piracy — Warfare, sea — Exclusive economic zone — Ports — Flag state — UNCLOS (UN Convention on the Law of the Sea)

Published under the auspices of the Max Planck Foundation for International Peace and the Rule of Law under the direction of Rüdiger Wolfrum.

A. Historical Background

Perhaps the first mariners ventured to sea without fear of their own sovereign or some other, but the projection of State power offshore soon followed marine commerce. At least as early as the 15th century BC, Greek sea power asserted itself in the waters of the eastern Mediterranean Sea against piracy and in regulation of seaborne trade. In their day, the Romans followed suit, and in their wake, various Italian city States in similar fashion controlled for a time the Tyrrhenian and Adriatic Sea[s] and the Ligurian Gulf. Eventually, the kings of Spain and Portugal asserted dominion over three of the oceans, while both northern European lords and Chinese emperors claimed and attempted control of their neighbouring seas and trade routes.

Out of the international friction that naturally ensued, there emerged in the 17th century among the sea powers of Europe a contrary legal proposition: that the high seas were free, that is, beyond the dominion of any particular sovereign power (Sovereignty). Hugo Grotius, a Dutch jurist, made the claim in print, if not first then most persuasively, in his works Mare liberum and De jure belli ac pacis, while John Selden of England led a theoretical defence of the status quo with his treatise Mare Clausum. Gradually, as national interest dictated, the notion of Grotius that no sovereign should control the high seas was embraced by more and more States (see also Law of the Sea, History of). Eventually, sufficient agreement transformed it into an axiom of international law, albeit one imperfectly applied. That on the high seas no State may interfere with the navigation of vessels under the protection of another is today the law of nations universally espoused (Navigation, Freedom of). Meanwhile, a different rule applies inshore, conceding dominion to the coastal sovereign. Both rules have been codified in the Convention on the High Seas (1958) and the United Nations Convention on the Law of the Sea (1982; Law of the Sea).

B. Interdiction in Peacetime as Coastal Police Action

In time of peace, any coastal State, for the purpose of enforcing its domestic laws, may interrupt the voyage in its territorial waters of a vessel under its own protection or that of another State. For a long time, territorial waters were generally accepted as reaching offshore to a distance of three nautical miles or one marine league. Today, they are generally accepted as reaching to a distance of 12 nautical miles, or four marine leagues (Territorial Sea).

In addition, contemporary international law allows any coastal State to husband marine resources, including both livestock and minerals, in an exclusive economic zone (‘EEZ’) that may reach as far from shore as 200 nautical miles, so that, for this limited purpose, a sovereign may control navigation in such a zone as it may in its territorial waters (see also Marine Living Resources, International Protection). This limited protectorship is codified in Art. 57 UN Convention on the Law of the Sea.

The dominion of littoral sovereigns over territorial seas is limited by the right of free (or innocent) passage. Innocent passage guarantees to foreign vessels transit without interference, provided that they conform to municipal law and hew to internationally recognized sea lanes. When they do not, they expose themselves to law enforcement by interdiction.

When visiting distant ports, non-governmental ships under any flag risk seizure and detention as security in ordinary civil actions to which they relate. Known as arrest, this practice has a long history and is widely accepted by flag sovereigns. It is standardized in the International Convention for the Unification of Certain Rules Relating to the Arrest of Sea-Going Ships ([adopted 10 May 1952, entered into force 24 February 1956] 439 UNTS 193), to which more than 70 States are parties, and the International Convention on Arrest of Ships ([adopted 12 March 1999, entered into force 14 September 2011] 2797 UNTS 3), to which only eleven States are parties. Compensation is generally available from the initiating party for malicious arrest, but not for arrest that is merely mistaken. Almost always, vessels are arrested while they are berthed. Very rarely, vessels are arrested while they are underway, due in part to the impracticality of such intercepts. Arrest of a foreign-flagged vessel in innocent passage of the territorial sea is persistently controversial. Neither arrest convention speaks to the matter. Art. 28 UN Convention on the Law of the Sea allows arrest for the execution of a judgment only of liabilities incurred by the vessel itself during that particular transit, but says nothing about arrest as pre-judgment security for a civil action pending at the time of arrest. Art. 38 UN Convention on the Law of the Sea forbids arrest during straits passage, but States bordering straits differ on whether Art. 38 shields only vessels flagged by another State party to the convention or universally as an expression of customary law.

C. The Privilege of Hot Pursuit

Agents of a State attempting to enforce its domestic law are entitled to continue their pursuit of a vessel under the protection of another sovereign even after she has escaped the pursuing State’s territorial waters. This privilege of hot pursuit is codified in Art. 111 UN Convention on the Law of the Sea. The same privilege applies to pursuit in aid of a sovereign’s conservation of marine resources within its EEZ.

D. A Protocol of Escalating Intrusiveness

When circumstances warrant, a stop at sea can lead to close scrutiny and questioning by the interdicting vessel drawn alongside. From what is seen and heard may follow suspicions that justify a boarding party’s visit to inspect the stopped vessel’s papers, interrogate those aboard, and search below deck (Ships, Visit and Search). What any of these investigations reveals may justify its diversion under threat of force to port for further proceedings, and ultimately to its seizure and forfeiture.

For inconvenience suffered by the stopped vessel, no compensation is generally due, even when the suspicions that prompted the stop eventually prove unfounded. But for loss or damage suffered as a result of the stop, Arts 106, 110, and 111 UN Convention on the Law of the Sea dictate compensation. The right to free navigation of the high seas belongs to sovereigns, however, not to ships or their owners. For this reason, unless sovereigns have between themselves agreed differently, claims for compensation are entertained only from the flagging sovereign, provided it chooses to act on behalf of those with an interest in a stopped ship. On a similar basis, and according to the view prevailing among sovereigns with sea power, a stop without the consent of the flag State itself is not made lawful by the consent of the stopped vessel’s master (see also Flag of Ships).

E. Contemporary Regimes of High Seas Interdiction in Time of Peace

10 Outside a sovereign’s territorial waters, its power to interrupt a vessel’s voyaging extends generally only to those who have submitted in exchange for protection, and therefore sail under that sovereign’s flag. There are three traditional exceptions to the freedom of the seas that entitle a sovereign to interrupt, even on the high seas, the voyage of a foreign-flagged vessel: piracy, slavery, and unlicensed radio broadcast (Pirate Broadcasting). Authority for a sovereign to stop a vessel under another flag on suspicion of piracy is codified in Art. 105 UN Convention on the Law of the Sea. Authority to stop a vessel suspected of broadcasting unlicensed radio signals by any sovereign whose territory has been invaded by the signals is codified in Art. 109 UN Convention on the Law of the Sea. None of these exceptions allows a sovereign to stop another sovereign’s public vessel, that is, a vessel belonging to a navy, coast guard, or maritime police force (State Ships). It is sometimes asserted, but not universally agreed, that a coastal sovereign cannot interdict a foreign public vessel even in the coastal sovereign’s own territorial waters or EEZ when the foreign vessel is making an innocent passage or transit passage.

11 As free navigation is contingent on a protecting flag, any State may lawfully stop a vessel unprotected by any other State, that is, a vessel with no flag at all. This authority is codified in Art. 110 UN Convention on the Law of the Sea.

12 Apart from these traditional exceptions, authority to stop a foreign-flagged vessel on the high seas may be conferred by an embargo resolution of the UN Security Council in accordance with Art. 25 UN Charter. Recent examples include UN Security Council Resolutions 665 (1990) of 25 August 1990 (SCOR 45th Year 21; Iraq), 787 (1992) of 16 November 1992 (SCOR 47th Year 29; Serbia), and 875 (1993) of 16 October 1993 (SCOR 48th Year 125; Haiti).

13 In several modern multilateral conventions, various States have also agreed to reciprocal limitations on high seas navigation by vessels sailing under their flags. For purposes of combating drugs, weapons, illegal aliens, pollution, or terrorism, flag States have consented to interruptions of the voyaging of their vessels by the agents of law enforcement of another State, usually after prior consultation, and sometimes only when an observer of the flag State is aboard the interdicting vessel. Art. 1 International Convention relating to Intervention on the High Seas in Cases of Oil Pollution Casualties ([adopted 29 November 1969, entered into force 6 May 1975] [1970] 9 ILM 25), for example, authorizes a coastal State Party to take whatever measures are necessary, even those contrary to the freedom of the seas, when threatened with a grave and imminent threat from pollution resulting from a maritime casualty, but Art. 3 requires prior consultation with the flagging State Party (see also Marine Pollution from Ships, Prevention of and Responses to). A State Party to the United Nations Convention against Illicit Traffic in Narcotic Drugs and Psychotropic Substances ([adopted 19 December 1988, entered into force 11 November 1990] [1989] 28 ILM 497) is authorized by Art. 17 to stop, board, and search a vessel flagged by another State Party to the convention when the stopping sovereign reasonably suspects that the vessel is engaged in traffic described by the Convention, but only after obtaining specific permission from the flagging sovereign. Art. 8 Protocol against the Smuggling of Migrants by Land, Sea and Air, Supplementing the United Nations Convention against Transnational Organized Crime ([adopted 15 November 2000, entered into force 28 January 2004] GAOR 55th Session Supp 49, 65) similarly affords authority to stop and search a vessel flagged by another State Party to the Convention when the vessel is suspected of smuggling migrants. Art. 8bis Protocol of 2005 to the Convention for the Suppression of Unlawful Acts against the Safety of Maritime Navigation affords similar authority when a vessel is suspected of involvement in an offence described by the Convention, but allows the stopping sovereign to proceed without prior consultation in the event of imminent danger to the lives of those on board.

14 Sovereigns have found it expedient to supplement these multilateral conventions with bilateral agreements licensing each State Party to stop a vessel flagged by the other when circumstances warrant suspicion. In aid of its attempt to enforce a national prohibition in 1919 on sales of alcoholic beverages, the US by treaty obtained general agreement from several European States that it might on reasonable suspicion of alcohol smuggling stop and search private vessels protected by their flags. This privilege to stop on the high seas reached only as far as the stopped vessel was capable of voyaging in an hour. More recently, in an attempt to limit the dissemination of weapons of mass destruction the US, through the Proliferation Security Initiative, joined in boarding agreements in 2004 with Liberia, Panama, and the Marshall Islands, under whose flags of convenience large numbers of cargo ships find protection (see also Weapons of Mass Destruction, Counter-Proliferation). According to these agreements, each State Party is authorized to stop on the high seas and board any vessel flagged by the other party, on reasonable suspicion of weapons of mass destruction transport, but only after obtaining specific permission from the flagging State. Meanwhile, the US and various other States have joined in bilateral ‘shiprider’ agreements that license each State Party, on suspicion of trafficking in drugs or migrants, to stop vessels in the territorial waters and EEZs of the other, but only at the direction of an agent of the other at the scene aboard the stopping vessel (see also Human Trafficking; Narcotic Drugs and Psychotropic Substances).

15 In response to drug smuggling from elsewhere in the Americas, the United States has enacted the Drug Trafficking Vessel Interdiction Act of 2008. This law goes beyond the assertion of extra-territorial jurisdiction over un-flagged vessels suspected of ordinary wrongdoing. It makes criminal any navigation of an un-flagged submersible or semi-submersible vessel on the high seas with the intent to evade detection. Federal courts have upheld the law by reference to a provision in the Constitution of the United States that authorizes Congress to ‘define and punish Piracies and Felonies committed on the High Seas, and Offenses against the Law of Nations.’

F. Interdiction According to the Law of War at Sea

16 The rules are different in time of war (Naval Warfare). Well after freedom of high seas navigation was agreed internationally and hegemony partitioned satisfactorily in time of peace between sovereigns policing offshore and those offering their protection worldwide to marine commerce, consensus on the rules for naval war remained elusive. Eventually, the Crimean War (1853–56) brought together two formerly antagonistic powers, France and Great Britain, which had long disagreed about the law of war at sea not only for belligerents, but also for sovereigns electing neutrality (see also Neutrality in Naval Warfare). Combined operations by the fleets of these former adversaries made necessary a common understanding of the applicable rules and led to the publication of a Manual of the Law of Maritime Warfare in 1854 by two English barristers, Hazlitt and Roche. Their work drew on a wide array of national expressions of international law, the most noteworthy of which are the opinions of Sir William Scott, Lord Stowell, accompanying his judgments in sea capture cases before the English High Court of Admiralty from 1798 to 1828, a period of two world wars. General principles pertaining to capture and blockade were formally agreed in the Paris Declaration Respecting Maritime Law (Paris, Declaration of [1856]), marking the end of the Crimean War. Both rules and principles have continued to attract general consensus, notwithstanding the stress of such transforming developments as the general blockade of the Confederacy during the American Civil War and submarine warfare since World War I. Several restatements of the law of naval warfare have followed that of Hazlitt and Roche, the most recent being the San Remo Manual on International Law Applicable to Armed Conflicts at Sea (1984), Part V of which details rules for wartime interdiction, that is for interception, visit, search, diversion, and capture. What follows is a summary of those rules.

17 A belligerent sovereign is warranted by the law of war at sea to capture (Prize Law) and thereafter appropriate, vessels, private or public, of the enemy sovereign (Enemy Property). A belligerent sovereign is also warranted by the law of war to capture private vessels flagged by neutral sovereigns when caught conveying contraband for the enemy. From this follows warrant for a belligerent sovereign to stop an apparently neutral vessel when circumstances raise reasonable suspicion regarding either the vessel’s true identity or the nature of her cargo. A belligerent sovereign is also warranted by the law of war to blockade the ports of its enemy, and to capture vessels voyaging in defiance of that blockade, even those of neutral sovereigns. From this follows warrant for a blockading sovereign to stop an indisputably neutral vessel suspected of violating or ‘running’ a blockade. When the capture is not warranted, those with an interest in the ship may recover from a prize court for damage or loss of ship and cargo (see also International Prize Court [IPC]). They may also recover for the delay of a stop unwarranted by law, and those who prevail on their claim of lawful navigation may recover as well for undue delay in the adjudication of their claims and restoration of their property (Prompt Release of Vessels and Crews).

G. Assessment and Conclusion

18 The international law relating to State interference with navigation sensibly accommodates two interests sometimes in conflict. The overarching principle of free navigation affords to seaborne commerce the simplicity of serving but one master, the sovereign by whom the vessel has been promised protection. Sensible exceptions in the customary law afford those State protectors license to pursue outlaws universally deplored. That States may exchange or otherwise agree broader licences to stop their flagged vessels affords a versatile tool for the evolution of new reconciliations responding to new conditions, allowing eventual incorporation of the fittest of these innovations in the general law of nations. So far, such agreed limitations on the freedom of the seas have done little harm and allowed much good.

19 Ship owners would prefer a law of compensation more accommodating of their interests in two ways. First, they would welcome general acceptance by States with sea power of their rights to assert directly their own claims against a stopping sovereign, without having to persuade their flagging State to take up the cause. Second, they would welcome general acceptance that economic loss suffered on an unlawful stop deserves compensation as much as physical loss or damage. Both of these changes erode the immunity of sovereigns and are therefore difficult to persuade, however equitable. Yet ship owners have long been heard in prize courts on their own claims to compensation, including compensation for the cost of undue delay in release, for wrongful capture in time of war, when it might be conceded that a sovereign deserves greater immunity for the collateral damage of war prosecution.

20 The law of interdiction at sea was once conveniently binary in form, with rules constraining sovereigns in the exercise of sea power in peace and war. Today, that distinction is increasingly blurred in a world where sovereigns feel obliged to police in concert and wage war asymmetrically. Where once their national interests persuaded sovereigns to accept the high seas as beyond reach of their power, now such interests apparently persuade instead cooperative power projection. This trend toward more interdiction is better understood to manifest not the obsolescence of the Grotian principle, but its evolution.

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