ASIL Insights

 NATO is preparing to interdict deliveries by sea of refined oil bound for Yugoslavia, as a means of ensuring that NATO's bombing of Serbian oil refineries will not be neutralized by the supply of refined oil from other sources.  France and Italy have raised a question whether such interdiction at sea would violate international law. 

 International law provides that ships on the high seas are subject to the exclusive jurisdiction of the flag state, with very few exceptions.  Ships passing through territorial waters are also entitled to be left alone, so long as they are in innocent passage.  Delivery of oil and other goods on merchant ships would normally be an exercise of the right of innocent passage.  Even if passage were not innocent in a particular instance, only the coastal state would normally have the right to interrupt it in its territorial waters. 

 Traditionally, these rules have been subject to some exceptions in time of war.  The navy of a combatant state could blockade the ports of an enemy state, if the blockade was applied to all ships and was effective.  NATO does not contemplate a blockade of all ships. 

A combatant could also interdict contraband at sea, even without a full-scale blockade.  The clearest form of contraband, "absolute contraband," consists of arms, ammunition and other purely military equipment.  These items could be interdicted in wartime.  "Conditional contraband" includes oil and other items that could have civilian as well as military uses, and could be interdicted only if destined for the military.  Pentagon officials reportedly are relying on the right to intercept contraband in time of armed conflict, as one of the legal justifications for the planned NATO action at sea. 

 The traditional law of blockade and contraband developed in a time when international law had little to say about the circumstances under which the use of armed force was or was not justifiable.  With the advent of the United Nations Charter in 1945, the use of armed force became legally justifiable only under certain circumstances, such as proportional self-defense (individual or collective) against armed attack, enforcement action if authorized by the U.N. Security Council, and perhaps limited forms of humanitarian intervention.  It is doubtful that the traditional right of blockade or seizure of contraband from ships flying the flag of a noncombatant state survived into the U.N. era, unless the use of armed force is itself legally justifiable under the circumstances just mentioned.  The principal legal arguments in support of NATO's use of armed force against Serbia are based on extensions of collective self-defense and humanitarian intervention.  (For fuller exposition of the legal issues regarding NATO's use of armed force against Serbia, see the ASIL Flash Insight of March 25, 1999, and the responses thereto on the ASIL web site, <www.asil.org>.) 

 In March 1998 the Security Council, acting under Chapter VII of the U.N. Charter, imposed an embargo on the supply to Yugoslavia of "arms and related matériel of all types, such as weapons and ammunition, military vehicles and equipment and spare parts for the aforementioned."  S.C. Res. 1160.  The Council called on all states and regional organizations to act strictly in conformity with the resolution and created a committee to monitor compliance, but did not expressly authorize NATO or any states to enforce it.  Like other legal instruments, however, the resolution is subject to interpretation.  Pentagon officials reportedly are relying on it, as well as on the law relating to contraband, as authority for NATO interdiction of oil supplies bound for Serbia. 

 In recent years the Security Council has imposed comprehensive trade embargoes on Iraq, and on Serbia-Montenegro during the Bosnian conflict, and has later expressly authorized states to take the necessary measures to make the embargoes effective.  Those authorizations under the Council's Chapter VII powers have trumped the rights of flag states to have their merchant ships be free from boarding at sea, so long as the interdicting ships were simply acting to enforce the Council's embargoes.  It was not necessary to rely on traditional rights of blockade or seizure of contraband, since the Council had legitimated the interdictions.  The questions France and Italy have raised about the current plan to interdict oil shipments to Serbia are that the Council has not expressly embargoed such oil shipments and has not expressly authorized interdiction, so the planned NATO action may be vulnerable on international law grounds insofar as it is to be carried out against ships flying the flags of non-NATO countries that object to the interdiction. 

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The purpose of ASIL Insight is to provide concise and informed background for developments of interest to the international community. The American Society of International Law does not take positions on substantive issues, including the ones discussed in this Insight. 
About the Author: Frederic L. Kirgis is Law School Association Alumni Professor at Washington and Lee University School of Law. He has written a book and several articles on United Nations law, and is a member of the Board of Editors of the American Journal of International Law.