Was the US-led attack on Iraq justified? The question comes from all corners of the globe, and answers are varied. Our collective response should be to cooperate in thoughtfully examining the practical constraints and legal limits to military intervention. The issue is not black-and-white, but multifaceted, and only by addressing it head-on can our international community hope to reach a consensus that will cement genuine autonomous international security for all.

As a cornerstone of international law for more than 350 years, the principle of non-intervention protected a range of different interests. Originally, it protected the sovereign prerogatives of the crowned heads who ruled Europe. While monarchies are not totally obsolete, the principle of non-intervention is now more likely to protect the democratic systems of self-determination and popular sovereignty. It has always helped to promote international peace and stability by discouraging the use of force against the territorial sovereignty and political independence of states. Today, both the reasons for the principle and the necessary exceptions to it can best be understood in terms of human rights.

When the current system of international law began to develop in Europe, it was built upon new rules of sovereignty and non-intervention. This system, unlike that of the hierarchical Holy Roman Empire that preceded it, is founded on the idea that each state is independent and has the same set of sovereign rights. Those who took responsibility for order and justice within the territorially-based state had all the rights of sovereignty under international law, including the exclusive right to make and enforce laws within that state. The principle of non-intervention promotes the peaceful coexistence of autonomous sovereign states by banning each of them from the use of force within the territory of the others.

International law recognizes each state’s rights of sovereignty and territorial integrity but cannot guarantee that other states will respect those rights. The international legal system is weak in that it lacks the centralized legislative and judicial organs and coercive executive powers to enforce the rule of law at the national level. Due to this weakness, states must often rely upon self-help to protect their rights under international law. The classic form of self-help is self-defense.

The Right of Self-Defense

The most notable exception to the general principle of non-intervention stems from the right of self-defense. Customary international law develops when the behavior of states over time indicates they have accepted a rule of law. Under that law, two essential conditions limit the right of states to use force in self-defense. First, the use of force must be necessary. In an 1841 letter to British Minister of Foreign Affairs Henry Stephen Fox, US Secretary of State Daniel Webster described this requirement as “a necessity of self-defense, instant, overwhelming, leaving no choice of means, and no moment for deliberation.” The second requirement is that the acts of self-defense must be proportionate to the threat. This customary standard does not condition the right on a prior armed attack.

The rules of international law are built upon the premise that states, like people, have a natural right to defend themselves against the imminent threat of harm. Article 51 of the UN Charter states that “[n]othing 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.” To the extent that self-defense is an inherent right, the use of force in preemptive self-defense could be justified even without a prior armed attack. This topic raises difficult issues of how to define and apply workable legal standards in matters affecting national security.

Intervention on Behalf of Human Rights

Proponents see humanitarian intervention as a fundamental exception to the principle of non-intervention. The basis for this exception is the idea that the governments of sovereign states hold rights under international law only if they fulfill certain obligations, including the obligation to respect the fundamental rights and interests of the governed. As far back as 1625, Hugo Grotius noted in The Law of War and Peace that those rulers who “provoke their people to despair and resistance by unheard of cruelties, having themselves abandoned all the laws of nature, they lose the rights of independent sovereigns, and can no longer claim the privilege of the law of nations.” This view was reinforced by developments at the national level, including such watershed events as the 1688 Glorious Revolution in England, the 1776 American Revolution, and the 1789 French Revolution. These events redefine the relationship between state and individual under both national and international law. The monarchies who exercised sovereignty in 17th century Europe were all sidelined or replaced. The values of democracy and popular sovereignty that brought such profound domestic changes had an effect upon international law as well. These changes accelerated in the 20th century as international law moved farther away from its original focus on the state-centered rights of sovereignty and began to stress respect for fundamental freedoms as a standard of governmental legitimacy. Nonetheless, the doctrine of humanitarian intervention remains quite controversial especially since the adoption of the UN Charter in 1945.

Intervention and Aggression

One key rationale for the principle of non-intervention is to promote the order and stability that are essential to the full enjoyment of human rights through local governmental rule. In his 1941 “four freedoms” speech, US President Franklin Roosevelt looked forward to a world in which all would enjoy “freedom from fear,” once armaments had been reduced to the point at which “no nation will be in a position to commit an act of physical aggression against any neighbor, anywhere in the world.”

The concepts of aggression and intervention are quite distinct, if related. Unlike intervention, which may at times be justified, aggression is an international crime that is unjustified by definition. Several members of the Nazi High Command were convicted of crimes against peace, defined by the Nuremberg tribunal as “planning, preparation, initiation or waging of a war of aggression, or a war in violation of international treaties, agreements or assurances.” In 1974, the UN General Assembly adopted a resolution defining aggression as “the use of armed force by a State against the sovereignty, territorial integrity or political independence of another State, or in any other manner inconsistent with the Charter of the United Nations.” The significance of this resolution is limited, however, because Article 39 of the Charter clearly states that Security Council alone is to determine the existence of aggression. The definition merely restates the language of Article 2(4) of the UN Charter and does nothing to resolve the inherent ambiguities.