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World Court Digest

Summaries of the Decisions

Legality of the Threat or Use of Nuclear Weapons

Advisory Opinion of 8 July 1996

On 15 December 1994, the United Nations General Assembly, by resolution 49/75 K, decided to request an advisory opinion from the Court on the following question: "Is the threat or use of nuclear weapons in any circumstance permitted under international law?". The request was submitted to the Court on 6 January 1995.

In its advisory opinion, the Court first examined the question of its jurisdiction. Some states had argued that the question of the legality of threat or use of nuclear weapons fell outside the scope of the Assembly's activities. The Court rejected this view, leaving open the question if requests by the Assembly were restricted to the scope of its activities. It held that even if this were so, the jurisdiction of the Court was established, because the request of the Assembly was closely connected with its general activities. Moreover, the political aspects connected with the request did not deprive the question of its legal character. The Court emphasized its discretion to give an advisory opinion, but stressed that refusals had to remain confined to exceptional cases. It found no compelling reason against delivering an opinion and rejected views of states which had contended that the questions was framed in too vague and abstract terms, that there existed no specific dispute on the subject matter and that a reply from the Court might adversely affect disarmament negotiations and the work of the United Nations.

In the view of the Court, several areas of international law contained rules possibly governing the threat and use of nuclear weapons. Among these were human rights law, especially the right to life, which, however, did not permit conclusions independent from the law of armed conflict. Equally, the prohibition of genocide covered the use of nuclear weapons only in specific circumstances. And international environmental law did not contain rules on nuclear weapons, but also referred to the law of armed conflict. The most pertinent areas of international law were thus the rules relating to the use of force and the law of armed conflict.

The law on the use of force, however, did not allow the Court to draw definite conclusions on the legality or illegality of the threat or use of nuclear weapons. The Court stated that self-defence as an exception to the prohibition of the use of force did not refer to specific weapons, but that, under Article 51 of the UN Charter, self-defence was subject to the conditions of necessity and proportionality. The latter did not in itself exclude the use of nuclear weapons in all circumstances. But the profound risks emanating from such use had to be borne in mind by states assessing the criterion of proportionality. Moreover, the mere threat to use nuclear weapons would be illegal if the use of force itself was illegal.

The Court went on to examine if there existed specific rules in international law regulating the legality or illegality of recourse to nuclear weapons per se. It first noted that the illegality of the use of certain weapons as such did generally not result from an absence of authorization but from a specific prohibition. It did not seem to the Court that the use of nuclear weapons could be regarded as specifically prohibited by the Hague Declarations of 1899, the Hague Regulations of 1907 or the Geneva Protocol of 1925. It rather found that more recent regulations concerning possession, manufacture and testing of nuclear weapons showed an increasing concern in the international community with these weapons, and that their future general prohibition might evolve. But neither from regional prohibitions nor the Treaty on the Non-Proliferation of Nuclear Weapons emerged an already established rule of that content, as several nuclear-weapon states had specifically reserved their right to use nuclear weapons in certain circumstances under these instruments. Likewise, no customary rule existed, because a clear opinio iuris in favor of a prohibition was not to be found among the members of the international community. The Court pointed out that the adoption each year by the General Assembly, by a large majority, of resolutions declaring the use of nuclear weapons illegal and requesting member states to conclude a convention on their prohibition, revealed the desire of a very large number of states to establish such a rule. But its emergence was hampered by the still strong adherence to the doctrine of deterrence.

The Court then examined whether general rules of international humanitarian law prohibited the threat or use of nuclear weapons. It identified three cardinal principles of humanitarian law. The first was the distinction between combatants and non-combatants and the principle that states must never make civilians the object of attack and must never use weapons incapable of distinguishing between civilian and military targets. The second principle was the prohibition to cause unnecessary suffering to combatants. The Court found the third principle in the Martens Clause as embodied in Art. 1 para. 2 of the Additional Protocol I of 1977, according to which in cases not covered by international instruments, civilians and combatants remained under the protection of the principles of international law derived from custom, from the principles of humanity and from the dictates of public conscience. The fundamental humanitarian rules nowadays constituted intransgressible principles of international customary law. Moreover, the majority of rules embodied in treaties for the codification of humanitarian law had already become customary law; but the Court left open to what extent these rules formed part of ius cogens. Despite the fact that the conferences leading to the adoption of the Geneva Conventions of 1949 and the Additional Protocols of 1977 left nuclear weapons aside, according to the Court, the rules of humanitarian law were in principle applicable to those weapons, as otherwise the intrinsically humanitarian character of these rules for all kinds of warfare would be disregarded. Likewise, the principle of the inviolability of neutral states was of a customary character and applicable to all international armed conflict, whatever type of weapons might be used.

The conclusions to be drawn from the applicability of these rules were, in the view of the Court, less clear. Certainly, having regard to the unique characteristics of nuclear weapons and the risks associated with them, their use seemed scarcely reconcilable with respect for the humanitarian rules. Nevertheless, the Court considered that it could not conclude that the use of nuclear weapons was unlawful in any circumstance. It especially pointed to the fundamental right of every state to survival, and thus its right to resort to self-defence in accordance with Article 51 of the Charter, when its survival was at stake. Furthermore, it considered the policy of deterrence, which had found strong adherence. In view of the present state of international law as a whole, the Court was led to observe that it could not reach a definitive conclusion as to the legality or illegality of the use of nuclear weapons by a state in an extreme circumstance of self-defence, in which its very survival would be at stake.

The Court finally emphasized that international law and the stability of the international order would suffer from the continuing difference of views with regard to the legal status of nuclear weapons. The most appropriate means of overcoming this state of affairs was complete nuclear disarmament. In the view of the Court, an obligation to achieve this result was contained in Article VI of the Non-Proliferation Treaty, by which the parties undertook to pursue negotiations in good faith on a treaty on general and complete nuclear disarmament. This obligation was reinforced by several resolutions of the General Assembly and reaffirmed by the Security Council.

President Bedjaoui and Judges Herczegh, Shi, Vereshchetin and Ferrari Bravo joined declarations; Judges Guillaume, Ranjeva and Fleischhauer appended separate opinions; and Vice-President Schwebel and Judges Oda, Shahabuddeen, Weeramantry, Koroma and Higgins dissented. The most common subject of the opinions was the inconclusiveness of the Court's findings. President Bedjaoui emphasized that this reflected the current legal uncertainty on the status of nuclear weapons; in the case of extreme circumstances neither legality nor illegality of their use could be determined. Judge Guillaume, however, interpreted the advisory opinion as implicitly recognizing a right of states to use nuclear weapons in those extreme circumstances. Vice-President Schwebel criticized the Court for leaving the question of legality open, thereby discarding the legal progress of the twentieth century and declaring that international law had nothing to say when it came to the supreme interests of states. According to Judge Koroma, the Court should have performed its judicial function and decide the case. Judge Higgins was also opposed to the finding of a non liquet as this was no part of the Court's jurisprudence. On the substantive issue of legality, Vice-President Schwebel and Judges Guillaume and Fleischhauer expressed their opinion that international law permits the conclusion that in extreme circumstances the use of nuclear weapons was legal. Judges Shahabuddeen, Weeramantry and Koroma stated that even then the use of such weapons had to be regarded as unlawful. In particular, Judges Shi and Ferrari Bravo emphasized that the policy of deterrence, in their view, did not have any legal value.