Exclusion Zones in the Law of Armed Conflict at Sea: Evolution in Law and Practice
92 International Law Studies 153 (2016)
Stockton Center for the Study of International Law
Maritime exclusion zones have been described as “one of the most controversial issues in the law of armed conflict at sea” and as an issue “that remains unresolved.” Part of the reason for the controversy relates to the potential infringement on the freedom of the high seas which, since the time of Grotius, has been seen as open to all States. Another part of the explanation relates to the lack of consistent State practice and the diversity of States’ views on the subject of exclusion zones. State parties to armed conflicts in which exclusion zones were utilized took the view that they were justified, either for an exceptional reason, for example, as a belligerent reprisal, or due to a rule of law that authorized them. The justifications thus varied considerably, with significant consequences for when exclusion zones could be used. By contrast, States that were not parties to the armed conflicts criticized them, sometimes as unlawful for interfering with the freedom of the high seas, or remained silent on their legality. This difference of opinion extended to commentators. Whereas some commentators observed in no uncertain terms that exclusion zones were unlawful, others expressed the view, in equally clear terms, that exclusion zones were lawful. The uncertainty was not helped by different terms being used to describe the same practice, such as “war zones,” “exclusion zones” and “barred areas,” and by certain similarities with associated concepts such as “defensive bubbles,” the “immediate area of operations,” and “blockades.”
This article traces the evolution in the law and practice of exclusion zones and argues that the zones have gone through three distinct phases. The first phase of the exclusion zone—and Part II of the present article— corresponds to the use of exclusion zones in the Russo-Japanese War of 1904–5. In that war, exclusion zones were defensive in character, modest in size and located adjacent to the State that authorized their creation. Part III explores the second phase of their evolution, which saw them transformed into something rather different. During the First World War, and in a number of wars and armed conflicts that followed, if a vessel was within an exclusion zone, it was deemed susceptible to attack. This was true regardless of whether the vessel was a neutral or belligerent one. Exclusion zones of this period were also far larger in size than the exclusion zones of the Russo-Japanese War and were located, in certain instances, at quite some distance from the coast of the State that authorized them. The start of the third (and present) phase of exclusion zones, discussed in Part IV, can be traced to the San Remo Manual on International Law Applicable to Armed Conflicts at Sea, which was adopted in 1994. That Manual transformed the law and practice of exclusion zones. In particular, it separated out the establishment of the zone from the enforcement of the zone and specified that the same law applies within the zone as outside it. It also set out regulations for the zones should they be created. The San Remo Manual has had a considerable effect on States’ views of exclusion zones, as is evident from the manuals of a number of States that have been published since the San Remo Manual. The San Remo Manual thus ushered in a third phase of exclusion zones, one that is fundamentally different from the phases that preceded it.
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 Christopher Michaelsen, Maritime Exclusion Zones in Times of Armed Conflict at Sea: Legal Controversies Still Unresolved, 8 JOURNAL OF CONFLICT & SECURITY LAW 363, 364 (2003)
 See HUGO GROTIUS, THE FREEDOM OF THE SEAS OR THE RIGHT WHICH BELONGS TO THE DUTCH TO TAKE PART IN THE EAST INDIAN TRADE 28 (James Brown Scott ed., Ralph Van Deman Magoffin trans., Oxford Univ. Press 1916) (1608); Convention on the High Seas art. 2, Apr. 29, 1958, 13 U.S.T. 2312, 450 U.N.T.S. 82; United Nations Convention on the Law of the Sea art. 87, Dec. 10, 1982, 1833 U.N.T.S. 397 [hereinafter UNCLOS].
 See Part III.
 Compare, for example, the views of GEORGE POLITAKIS, MODERN ASPECTS OF THE LAWS OF NAVAL WARFARE AND MARITIME NEUTRALITY (1998) with W.T. MALLISON JR., STUDIES IN THE LAW OF NAVAL WARFARE: SUBMARINES IN GENERAL AND LIMITED WARS 74 (1968) (Vol. 58, U.S. Naval War College International Law Studies).
 The term “exclusion zone” will be used in the present article, unless a different term is used by a party to an armed conflict, such as the term “war zone” in the Iran–Iraq armed conflict. See infra Part III.D.
 The immediate area of operations is “that area within which hostilities are taking place or belligerent forces are actually operating.” In that area, “a belligerent may establish special restrictions upon the activities of neutral vessels and aircraft and may prohibit altogether such vessels and aircraft from entering.” SAN REMO MANUAL ON INTERNATIONAL LAW APPLICABLE TO ARMED CONFLICTS AT SEA 183 (Louise Doswald Beck ed., 1995) [hereinafter SAN REMO MANUAL].
 A blockade is “the blocking of the approach to the enemy coast, or a part of it, for the purpose of preventing ingress and egress of vessels or aircraft of all States.” Id. at 176.
 SAN REMO MANUAL, supra note 6