Pre-emptive Action to Forestall Terrorism

Frederic L. Kirgis
June 04, 2002
According to news reports, President Bush and his advisors are developing a new national security strategy based on pre-emptive action against terrorist groups and states that are trying to develop weapons of mass destruction.  It has been reported that the new policy reserves the right to act even if the threat is not judged to be imminent.  The pre-emptive action would not necessarily involve armed force, but that option is not ruled out.
Under the Lotus Case, decided by the World Court in 1927, "the first and foremost restriction imposed by international law upon a State is that - failing the existence of a permissive rule to the contrary - it may not exercise its power in any form in the territory of another State."1 The right of self-defense is such a permissive rule, if the conditions of necessity and proportionality are met. U.N. Charter article 51 recognizes the inherent right of self-defense, "if an armed attack occurs" against a UN member state, until the Security Council has taken measures necessary to maintain international peace and security.  On its face, article 51 would not apply, and therefore would not be the permissive rule contemplated by the Lotus Case, if the defensive action is taken before any armed attack has occurred.
The UN Charter is a treaty binding upon the United States and other UN member states. The Vienna Convention on the Law of Treaties, which is widely thought to reflect customary international law, allows a party to a treaty to suspend the treaty's operation if circumstances constituting an essential basis of its consent have fundamentally changed in a way not foreseen when the treaty was entered into, and if the change radically transforms the extent of obligations still to be performed under the treaty.  It may be argued that the same principle would apply to specific provisions in a treaty.  Thus it may be argued that circumstances have so fundamentally changed since 1945, when the UN Charter was adopted, that the "armed attack" restriction can no longer be taken literally. Clearly, the threat of large-scale terrorism with weapons of mass destruction was not foreseen when the Charter was drawn up, and one could argue that the other conditions of the Vienna Convention allowing suspension of a treaty obligation under changed circumstances have been met as well.
Even if the "armed attack" restriction in article 51 need not be taken literally as a treaty limitation on the use of self-help in an age of large scale terrorism, customary international law has supplied its own limitations on pre-emptive self defense. Under a 19th century formulation by the U.S. Secretary of State in the Caroline incident, reaffirmed by the Nuremberg Tribunal after World War II, the necessity for pre-emptive self defense must be "instant, overwhelming, and leaving no choice of means, and no moment for deliberation."2  If, as noted above, the new US policy reserves the right to act in self defense even when the terrorist threat is not imminent, the Caroline test would not be met.
But customary international law is not static.  It may be modified over time by new assertions of rights, if other states acquiesce in those assertions.  Thus the reactions of other states to the new US policy could affect the rule of the Caroline case.  Moreover, precedents based on specific fact situations may be distinguished when the relevant facts change significantly.  As in the case of the argument against taking UN Charter article 51 literally, it could be argued that the Caroline test is inapplicable because it was formulated in an era, and under circumstances, quite unlike those prevailing today.  Similarly, the Nuremberg Tribunal, when it reaffirmed the Caroline test in the context of World War II, was dealing with a situation distinguishable from the current scene.  Even so, the basic requirements of necessity and proportionality for the lawful exercise of the right of self-defense would remain in force.
There are also questions relating to tactics.  If the United States were to attempt to remove a foreign head of state from office (leaving aside what it might do during an actual war), the analysis would differ depending on the method used.  If it were done by supporting opposition groups within the foreign country who are seeking to remove the leader by the use of force, what the World Court said in the 1986 case of Nicaragua v. United States would be relevant:
The Court therefore finds that no such general right of intervention, in support of an opposition within another State, exists in contemporary international law.  The Court concludes that acts constituting a breach of the customary principle of non-intervention will also, if they directly or indirectly involve the use of force, constitute a breach of the principle of non-use of force in international relations.3
The Court decided in that case that the United States, by supporting and aiding the "Contras" in their attempt to overthrow the Nicaraguan government, had breached its obligation under customary international law not to intervene in the affairs of another State.4
A direct assassination attempt by the government of one state against a head of another state would be even more problematical.  For example, earlier this year the World Court enunciated a rule protecting the inviolability of a top government official "against any act of authority of another State which would hinder him or her in the performance of his or her duties," even if the official is suspected of having committed war crimes or crimes against humanity.5 That case involved an arrest warrant issued by Belgian authorities against the Foreign Minister of the Democratic Republic of the Congo, not an assassination attempt.  But the principle of the case would extend, a fortiori, to an assassination attempt against a head of state.
1  Case of the S.S. "Lotus" (France v. Turkey), PCIJ Series A, No. 10, at 18 (1927).
2  The Caroline (exchange of diplomatic notes between Great Britain and the United States, 1842), 2 J. Moore, Digest of International Law 409, 412 (1906).
3  Case Concerning Military and Paramilitary Activities in and against Nicaragua (Nicaragua v. United States), 1986 ICJ Rep. 14, 25 ILM 1023 (1986), para. 209. 
4 The Court did not have the advantage of hearing the US position on this issue, because the US had withdrawn from the proceedings after the Court found that it had jurisdiction to hear the case.
5 Case Concerning the Arrest Warrant of 11 April 2000 (Democratic Republic of the Congo v. Belgium), 2002 ICJ Rep. ___, 41 ILM 536 (2002), paras 54, 58.
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.