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January 01, 2003

Jus ad Bellum: Law Regulating Resort to Force

by Nicole Deller and John Burroughs

In September 2002 the Bush administration unveiled a novel doctrine articulating a right to take preemptive military action against threats arising from possession or development of weapons of mass destruction and from links to terrorism, “even if uncertainty remains as to the time and place of the enemy’s attack” (National Security Strategy of the United States of America). Now invoked as a basis for the country to wage war on Iraq, the doctrine is incompatible with international legal constraints on resort to force, traditionally known as jus ad bellum. This article examines the current status of jus ad bellum.

Force Under International Law

Adopted in the wake of World War II and proclaiming the determination “to save succeeding generations from the scourge of war,” the United Nations Charter (Charter) established a prohibition on the use of force to resolve disputes among states. Article 2(4) bans the threat or use of force (1) against the territorial integrity of a state, (2) against the political independence of a state, and (3) in any other manner inconsistent with the purposes of the UN. The Charter contains two exceptions to the prohibition, authorizing the Security Council to use force on behalf of the United Nations to maintain peace and security, and recognizing the right of self-defense against an armed attack. These are the only bases for legitimate use of force generally accepted in     present-day international law.

Self-Defense. Article 51 of the Charter provides in part: “Nothing in the present Charter shall impair the inherent right of individual or collective self-defense if an armed attack occurs against a member of the United Nations, until the Security Council has taken measures necessary to maintain international peace and security.” The use of “inherent” acknowledges that the Charter does not create a right to self-defense; rather, the right preexists the Charter and is fundamental to the system of states. But the Charter also strictly limits self-defense, in that the triggering condition for its exercise is the occurrence of an armed attack.

This limitation prompted an ongoing debate whether the right to use force in anticipation of an attack, which existed prior to the Charter, remains in effect. Some scholars believe Article 51 should be read literally and therefore the right of anticipatory self-defense has been terminated. Others believe that Article 51 is an expression of intent not to limit the right of self-defense under customary international law. States generally have been reluctant to acknowledge a right of anticipatory self-defense under the Charter, preferring if necessary to interpret “armed attack” broadly to include actions incident to launching an attack. Christine Gray, International Law and the Use of Force, 111-15 (2000).

Anticipatory Self-Defense. The right to anticipatory self-defense under customary law has never been unlimited. One generally recognized formulation dating from the mid-nineteenth century is that set forth in a letter from U.S. Secretary of State Daniel Webster to British Minister Lord Ashburton, that the necessity for action must be “instant, overwhelming, and leaving no choice of means, and no moment for deliberation.” Since then, and especially since World War II, capabilities to launch devastating attacks with little advance warning have improved dramatically. Nonetheless, scholars have continued to affirm Webster’s restraints on legitimate self-defense, recognizing their value in inhibiting resort to war. A recent edition of a leading treatise states that self-defense may justify use of force under the following conditions: an attack is immediately threatened; there is an urgent necessity for defensive action; there is no practicable alternative, particularly when another state or authority that legally could stop or prevent the infringement does not or cannot do so; and the use of force is limited to what is needed to prevent the infringement. Oppenheim’s International Law, 9th ed., 412.

Assuming its continued relevance, application of the doctrine of anticipatory self-defense to the current crisis concerning Iraq is straightforward. Iraq has been accused of attempting to reconstitute the chemical, biological, and nuclear weapons and missile programs that were terminated or at least severely disrupted by the post-Gulf War inspections; but no definitive evidence has been presented that establishes Iraq’s possession of such weapons or missiles, or their current use to threaten the United States or its allies. Indeed, the months of ongoing, public deliberations on this matter strongly suggest that a state of immediacy does not exist. Further, absent an imminent attack, nonviolent options such as negotiation and verification that a state does not possess weapons that violate disarmament and nonproliferation norms should be pursued in all cases of suspected acquisition of weapons of mass destruction contrary to international law. This follows from the doctrine of anticipatory self-defense, which in Webster’s formulation allows force only if there is “no choice of means,” and, more broadly, from the Charter, which requires the peaceful resolution of disputes when possible.

National Security Doctrine. The same considerations apply more generally to the new U.S. doctrine quoted at the beginning of the article, which claims the right to act militarily against states based on potential threats arising from states’ possession or development of weapons of mass destruction and from links to terrorism. Although the doctrine has been in gestation for over a decade, it was given great impetus by the September 11 terrorist attacks. This is true even though expanding the scope of self-defense was not necessary to legitimize the military operations undertaken in Afghanistan in response to the attacks; these are generally acknowledged to fall under the existing right of self-defense. The Bush administration, however, contends that September 11 demonstrates that threats facing the United States, especially from weapons of mass destruction, have reached a magnitude that demands a far-reaching revision of jus ad bellum.

The articulation of what amounts to a doctrine of preventive war has met with a great deal of resistance. A rule permitting a military response to an uncertain threat absent immediate danger or exhaustion of peaceful alternatives is a standard ripe for abuse that would destabilize the Charter system of restraints on use of force that protects all states. Preventive war undertaken unilaterally by states also appears contrary to international law predating the Charter. The International Military Tribunal sitting at Nuremberg rejected defendants’ arguments that Germany was entitled to attack Norway to forestall an Allied invasion, finding that no such invasion was imminent. United States v. Goering, 6 F.R.D. 69, 100-01 (1946). Defenders of the new doctrine point to the 1981 Israeli air strike against the Osirak nuclear reactor in Iraq as an example of a beneficial preventive military action. In terms of the legality of the action, the Security Council condemned the strike as a violation of the Charter and of the “norms of international conduct.” S.C. Res. 487. From a practical standpoint, whether the strike aided in protecting Israel against an Iraqi nuclear weapon remains in dispute.

Enforcement Realities

When countries, especially powerful ones, exceed lawful limitations on the use of force, the international institutional response is typically limited. Examples are legion: the Security Council took no serious steps to end the major 1980s war between Iraq and Iran initiated by Iraq. The Security Council also attached no sanction to its condemnation of the Israeli attack on the Osirak facility. After the 1986 decision by the International Court of Justice enjoining the United States to end its support of Nicaraguan rebels, the United States vetoed a Security Council resolution occasioned by the decision but calling only generally for compliance with international law.

The failure of enforcement is endemic to the current structure of international law. The most important factor is that the body charged with responsibility to govern use of force, the Security Council, remains subject to veto power by the United States and other permanent members. These states and their allies frequently are the principal actors in uses of force. The International Court of Justice is a suitable venue for seeking redress against transgressing states only to the extent that involved states have accepted or would accept its jurisdiction. The International Criminal Court will not have jurisdiction over the crime of “aggression” unless and until agreement is reached on its definition and the treaty is amended: a process that will take at least a decade. Because both the will and the ability to respond to violations after they have occurred remains limited, in-depth deliberation is all the more important; prior to its initiation, discussions on the compatibility of use of force with international law must occur within governments, in the United Nations, and in the public sphere.

Authorized Force. The only generally recognized legitimate use of force other than self-defense is that directed or authorized by the Security Council to restore or maintain international peace and security. Chapter VII of the Charter establishes that force may be used for this purpose when the Security Council has determined the existence of a threat to peace, a breach of peace, or an act of aggression; and efforts to address the matter using measures short of force have failed or would be futile. The Charter originally envisaged that states would make their troops and facilities available for Security Council use pursuant to Article 43, essentially creating a standing force; but that arrangement never materialized. Instead, the Security Council delegates its authority to willing states on an ad hoc basis.

Implied Authorization. A central issue is whether a state may legally conduct military operations not authorized by the Security Council when the state believes international peace and security or humanitarian values are at stake. The issue was highlighted sharply by the 1999 U.S./NATO bombing of Yugoslavia and is at the forefront of the current debate over the U.S. confrontation with Iraq. In the Yugoslavia case, the United States argued, albeit not very strongly, that the use of force was implied by resolutions condemning Yugoslavia’s conduct in Kosovo. Given that Russia was likely to veto an explicit authorization of use of force, this argument carries little weight. Despite the lack of Security Council authorization, the action received considerable international support as a humanitarian intervention, evidenced in part by the 12-3 vote in the Security Council against a resolution condemning the bombing then under way.

As of December 2002, the Bush administration maintains with regard to Iraq that a Security Council resolution authorizing force is not required for a U.S.-led invasion of Iraq. S.C. Resolution 1441, adopted November 8, 2002, which imposes a strict inspection regime on Iraq, does not specifically authorize use of force and requires returning to the Security Council before resorting to force. Nonetheless, the White House contends that because the resolution “decides that Iraq has been and remains in material breach of all relevant resolutions,” the United States already has the authority to use force to ensure compliance with the new inspection regime should the Security Council choose not to use force. The logic behind the assertion is that (1) the Security Council previously authorized force in response to Iraq’s invasion of Kuwait; (2) authorization was suspended only pursuant to a cease-fire codified by Resolution 687; (3) Iraq is in breach of the cease-fire terms; and (4) the authorization therefore remains in effect.

The administration’s logic is flawed. Resolution 687 included the requirement that Iraq end its long-range missile and chemical, biological, and nuclear weapons programs; but the Security Council reserved for itself the power to make determinations regarding enforcement of the cease-fire terms. Paragraph 34 of the resolution states that the Security Council “[d]ecides to remain seized of the matter and to take such further steps as may be required for the implementation of the present resolution and to secure peace and security in the area.” Since then, although the Security Council repeatedly has found Iraq to be in a state of noncompliance, it has not clearly and specifically authorized the use of force to achieve compliance. When the Security Council has authorized force in other situations, it has employed language universally understood to authorize force, e.g., “all necessary means.” This applied to use of force in Korea in 1950; ejection of Iraq from Kuwait in 1990; and in Somalia, Haiti, Rwanda, and Bosnia in the 1990s. The U.S. claim that material breach by Iraq provides a basis for termination of the cease-fire ignores the fact that the Gulf War was an action authorized by the Security Council, not a state-versus-state conflict. Accordingly, only the Security Council can determine whether to end the cease-fire in response to material breach by Iraq. For the Security Council to credibly maintain international peace and security, it must “retain strict control over the initiation, duration and objectives of the use of force”; tolerance of actions based on implicit Security Council authorization “loosens the restraint on the use of force.” Jules Lobel & Michael Ratner, Bypassing the Security Council: Ambiguous Authorizations to Use Force, Cease-Fires and the Iraqi Inspection Regime, 93 A.J.I.L. 124, 125-31 (1999).

Implied authorization for force must be viewed in the context of the fundamental principles of the Charter. The Charter gives priority to the peaceful settlement of disputes and the nonuse of force. The Article 2(4) prohibition on the threat or use of force has been described by the International Court of Justice as a peremptory norm of international law from which states cannot derogate. Nicaragua v. United States, 1986 ICJ 14, ¶190. To date, the Security Council has authorized force only in response to actual invasion, lare-scale violence, or humanitarian emergency, not to potential threats of the kind the United States claims are posed by Iraq.

Humanitarian Intervention. In the 1990s, the Security Council and major states failed abjectly to respond effectively to large-scale atrocities in Rwanda and Bosnia. The later Kosovo war was justified on humanitarian grounds. In light of these and other developments, and building on long-standing concerns, scholars, some states, and UN Secretary-General Kofi Annan have called for building international capabilities for conflict prevention, including a capability for military intervention to prevent or limit massive human rights violations. The 2001 report of the International Commission on Intervention and State Sovereignty, The Responsibility to Protect, is representative of this view. A major issue is whether military intervention for humanitarian purposes is permissible when not authorized by the Security Council. The legal bases for humanitarian intervention absent Security Council authorization arguably could be found in the human rights clauses of the Charter, the 1948 Genocide Convention, and other international law. Alternatively, such intervention could be analyzed under a doctrine of necessity: although an act is not legally permitted, that it was done to prevent genocide or other crimes against humanity should condition the international community’s assessment and response.

Many states, especially those in the developing world that fear major power interference in their affairs, oppose arguments tending to legitimize intervention. It is fair to say, however, that should the Security Council continue to prove unable to act to prevent large-scale humanitarian atrocities, pressure will build for recognition of the lawfulness of humanitarian intervention by regional organizations or coalitions of states. As in the case of anticipatory self-defense, any such recognition should be subjected to stringent limiting conditions, among them demonstrated and immediate need, Security Council unwillingness to address the matter, exhaustion of non-forcible remedies, and an action narrowly tailored to achieve humanitarian ends.


Nicole Deller is a consultant to the Lawyers’ Committee on Nuclear Policy (LCNP) and principal editor ofRule of Power or Rule of Law? An Assessment of U.S. Policies and Actions Regarding Security-Related Treaties (2003). John Burroughs is LCNP executive director and author of The Legality of Threat or Use of Nuclear Weapons: A Guide to the Historic Opinion of the International Court of Justice (1998).