Legality of the Threat or Use of Nuclear Weapons

Let us look at the Public International Law case Legality of the Threat or Use of Nuclear Weapons. By a letter from December 19, 1994, filed in the Registry on January 6, 1995, the Secretary-General of the United Nations officially communicated to the Registry a decision taken by the General Assembly, by a resolution adopted on December 15, 1994, to submit to the Court, for advisory opinion, the following question: “Is the threat or use of nuclear weapons in any circumstance permitted under international law?” The resolution asked the Court to render its advisory opinion “urgently”. Written statements were filed by twenty-eight States, and subsequently written observations on those statements were presented by two States. In the course of the oral proceedings, which took place in October and November 1995, twenty-two States presented oral statements. On July 8, 1996, the Court rendered its Advisory Opinion. Having concluded that it had jurisdiction to render an opinion on the question put to it and that there was no compelling reason to exercise its discretion not to render an opinion, the Court found that the most directly relevant applicable law was that relating to the use of force, as enshrined in the United Nations Charter, and the law applicable in armed conflict, together with any specific treaties on nuclear weapons that the Court might find relevant.

The Court on the Public International Law case Legality of the Threat or Use of Nuclear Weapons discussed two procedural questions. (1) Did the Court have the competence to give an advisory opinion based on a request of the General Assembly? In other words, did the General Assembly have the competence to ask the Court for an advisory opinion on the above question? (2) If yes, were there any reasons that would compel the Court to decline to exercise its jurisdiction? The Court also discussed five substantive questions. (3) Did treaty or customary law authorise the use of nuclear weapons? (4) Did treaty or customary law contain a “comprehensive and universal” prohibition on the threat and use of nuclear weapons? (5) Should the threat or use of nuclear weapons be compatible with international humanitarian law and other undertakings of the law? (6) Will the threat or use of nuclear weapons be lawful in self-defense in situations where the very survival of the State is at stake? (7) Is there an obligation on States to work towards nuclear disarmament?

The Court concludes that neither customary law, nor treaty law, explicitly authorises the use of nuclear weapons (para. 52). Yet, it highlights that explicit authorisation is not required because the illegality on the threat or use of nuclear weapons does not stem from the lack of specific authorisation, but on a specifically formulated prohibition (the general principle is found in more details in “The Lotus case”). Next, it went on to examine if customary or treaty law prohibits the threat or use of nuclear weapons.

The Court concludes that there is no comprehensive and universal prohibition on the threat or use of nuclear weapons either in treat or customary law. In terms of treaty law, some States argued that the use of nuclear weapons would violate the right to life and other treaty-based human rights, prohibition on genocide, and rules relating to the protection of the environment. The Court says that none of these treaties provide a “universal and comprehensive” prohibition on the use of nuclear weapons. Then, the Court says that the “most directly relevant applicable law” is the U.N. Charter provisions relating to the use of force and those laws that govern armed conflict. However, it finds that both of these legal regimes also do not expressly prohibit, nor permit, the use of nuclear weapons. In terms of customary law, the Court finds that the opinio juris on the prohibition of the use of nuclear weapons differs amongst States, as reflected in the content and voting patterns of General Assembly resolutions, their views on deterrence and the non-use of nuclear weapons in the recent past. The Court finds that “The members of the international community are profoundly divided on the matter of whether non-recourse to nuclear weapons over the past fifty years constitutes the expression of opinio juris. Under these circumstances the Court does not consider itself able to find that there is such an opinio juris The emergence, as lex lata, of a customary rule specifically prohibiting the use of nuclear weapons as such is hampered by the continuing tensions between the nascent opinio juris on the one hand, and the still strong adherence to the practice of deterrence on the other”. The Court concludes that there is no comprehensive and universal prohibitions on the threat or use of nuclear weapons under treaty law or customary law.

Thus far, the Court has concluded that there are no provisions in international law that authorises or prohibits the threat or use of nuclear weapons by States. The Court now goes a step further to examine if the threat or use of these weapons is regulated under international law. In other words, should its use be compatible with the requirements of international law applicable in armed conflict (which includes international humanitarian law) and the U.N. Charter?

Continuing on the Public International Law case Legality of the Threat or Use of Nuclear Weapons, the Court finds as follows: “The Court had established that the U.N. Charter did not permit or prohibit the use any type of weapons. However, it finds that for the a threat or use of force in self-defense to be lawful under Article 51 of the U.N. Charter, the use of nuclear weapons must be necessary and proportionate to the armed attack against which self-defense is exercised. The Court says that the use of nuclear weapons may be proportionate in certain circumstances (the Court does not specify the circumstances)”. The Court goes on to hold that even if the threat or use of nuclear weapons is lawful under the U.N. Charter (in other words, when it is necessary and proportionate), it must still meet the requirements of laws regulating armed conflicts, including international humanitarian law and principles relating to neutrality. The Court finds that it cannot conclude that the recourse of nuclear weapons “would be illegal in any circumstances” or if the use of nuclear weapons was inherently and totally incompatible with international humanitarian law. In view of the unique characteristics of nuclear weapons the use of such weapons in fact seems scarcely reconcilable with respect for such requirements (relating to distinction and suffering). Nevertheless, “The Court considers that it does not have sufficient elements to enable it to conclude with certainty that the use of nuclear weapons would necessarily be at variance with the principles and rules of law applicable in armed conflict in any circumstance”. This was reaffirmed in the Court’s conclusion when it held that nuclear weapons were generally, and not absolutely, contrary to international law applicable in armed conflicts: “It follows from the above-mentioned requirements that the threat or use of nuclear weapons would generally be contrary to the rules of international law applicable in armed conflict, and in particular the principles and rules of humanitarian law”. The Court also finds that it could not reach a conclusion on the legality or illegality of the use of nuclear weapons in “an extreme case of self-defense”. The Court highlights the “fundamental right of every State to survival” and holds that “In view of the present state of international law viewed as a whole (and base on) the elements of fact at its disposal, the Court is led to observe that it cannot reach a definitive conclusion as to the legality of the use of nuclear weapons by a State in an extreme circumstance of self-defense, in which, its very survival would be at stake”. The Court didn’t elaborate on what would constitute an extreme case of self-defense nor address whether a State having nuclear weapons (a nuclear State) can use it in the defense of another non-nuclear State when that second State very existence is threatened.

The Court finds that there is an obligation “To pursue in good faith and bring to a conclusion negotiations leading to disarmament”. Other interesting aspects of the judgement that haven been dealt with in this post, in detail, includes paragraphs relating to the applicability of human rights and environmental law in times of armed conflict, policy of deterrence, and General Assembly’s contribution to the progressive development of customary law. This is what can be said concerning the Public International Law case Legality of the Threat or Use of Nuclear Weapons.