It is undeniable fact that State practice for some fifty (50) years clearly demonstrates the idea that possession of nuclear weapon per se is not illegal under international law. It is for this reason that most States consented and even supported the possession of nuclear weapons by the “Big Five” pursuant to the Treaty on Non-Proliferation of Nuclear Weapons (NPT). The perceived acquiescence by the international community of NPT has created the impression that these nuclear powers are legally entitled not only to possess, but also to use nuclear weapons under certain circumstances and to threaten their use. Vice-President Stephen Schwebel of the International Court of Justice opined:
This nuclear practice is not a practice of a lone and secondary persistent objector. This is not a practice of a pariah Government crying out in the wilderness of otherwise adverse international opinion. This is the practice five of the world’s major powers, of the permanent members of the Security Council, significantly supported for almost 50 years by their allies and other States sheltering under their nuclear umbrellas.
From the foregoing observation, it is crystal clear that this practice has been recognized, accommodated and to some extent, accepted by the majority of States forming part of the international community. The arguments posed by nuclear-weapons States are mainly based on the fundamental principle of independence and respect in the conduct of their foreign relations. It is precisely for this reason that they adopted the so- called, “policy of deterrence” to justify their position. Under this policy, in order to lessen or eliminate the risk of unlawful attack, states signal that they possess certain weapons to use in self-defense against any State violating their territorial integrity or political independence.
Under Article 2, par. 4 of the UN Charter, members of the United Nations shall refrain in their international relations from the threat or use of force against the territorial integrity or political independence of any state. This provision must be read in conjunction with Article 51 of the same charter recognizing every state’s inherent right of individual or collective self-defense if an armed conflict occurs. Clearly, the provisions cited do not refer to specific weapons. They apply to any use of force, regardless of the type of weapon employed. In the advisory opinion rendered by the World Court concerning the legality of nuclear weapons, it noted that the UN Charter neither expressly prohibits nor permits the use of any specific weapon. Accordingly, whatever the means of forced used in self-defense, the dual customary condition of necessity and proportionality and the law applicable to armed conflict apply, including such further considerations as to the very nature of nuclear weapons and the profound risk associated with their use. This pronouncement by the International Court of Justice implicitly affirms the right to use nuclear weapons under extreme circumstances in the exercise of legitimate self-defense. But as vividly pointed out by the court, the invocation of self-defense must comply with the principles of necessity and proportionality. As held in case of Nicaragua v. United States of America,” there is a specific rule whereby self-defense would only warrant measures which are proportional to the armed attack and necessary to respond to it, a rule well established in customary law.” Verily, the Proportionality principle thus not in itself excludes the use of nuclear weapons in all circumstances so long it complies with the principles and rules of humanitarian law. It must be stressed that in the said advisory opinion the court pointed out that mere possession of nuclear weapons would not constitute unlawful “threat” to use force contrary to Article 2 (4), unless the particular use of force envisaged would be directed against the territorial integrity or political independence of any state; or in any event that it were intended as a means of defense; such envisaged use of force would violate the principles of necessity and proportionality. Settled is the rule under international law that opinions rendered by the International Court of Justice are highly persuasive and entitled to great respect in resolving issues pertaining to international law. Likewise, decisions and opinions of the World Court offer direct evidence of the existence of a rule of international law.
One of the recognized primary sources of international law is customary law. In many occasions, international tribunals have been using international customs in resolving controversies involving questions and application of international law. In accordance with Article 38, par.1 (b), the International Court of Justice is directed to apply international custom in deciding disputes involving interpretation of international law. In addition, even national courts of most States when confronted with issues pertaining to general principles of international law, the most decisive and effective way in deciding the case is to rely on international customary law.
Declarations of legal principles and resolutions by the United Nations General Assembly are generally considered “recommendatory” in nature. As a rule, the General Assembly has no authority to enact international law; but if these resolutions are supported by all states they are an expression of opinio juris communis─ thus it becomes part of customary law. Clearly then, did Resolution 1653 gain overwhelming support from member-states? The response leaves much to be desired; for not only did it fail to gather support from all member-states, it likewise failed to secure the approval of all nuclear-weapon States.
It is therefore the view of this writer that a contrary opinion prevails. To support this contention, one need not look further; the Treaty on the Non-Proliferation of Nuclear Weapons provides us with an answer. The fact that said treaty allows possession of nuclear weapons by the five nuclear-weapon States highlights a startling recognition that such dangerous weapons may be used under highly extreme circumstances. It is imperative to note that in so far as customary law is concerned, there appears to be no hard-and-fast rule authorizing the threat or use of nuclear weapon or any other weapon in general. But if the situation calls for it, international customary law impliedly sanctions its ‘use’ on two compelling grounds: in the exercise of legitimate self-defense and if the dual customary conditions of “proportionality” and “necessity” are complied.
In sum, there can be no doubt that nuclear weapons may be used under the most looming circumstances signalling a major conflict─ when the very survival of a state is at stake. International law therefore must strike a balance between two compelling interests: state's inherent right to existence and self-defense vis a vis right to life.
NB: This is a recycled material. I've written this piece way back in 2002, one year before I entered law school.