Legality of the Threat or Use of Nuclear Weapons, Advisory Opinion of 8 July 1996

Advisory Opinion of 8 July 1996
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The Secretary-General of the United Nations requested an advisory opinion from the International Court of Justice on the following question: “Is the threat or use of nuclear weapons in any circumstances permitted under international law?”. The Court determined that it had the jurisdiction and competence to reply to the UN request according to Article 96, paragraph 1 of the charter of the United Nations, which allows the Court to serve its advisory function. Because the inquiry did not arise out of a dispute between two states, the Court accepted the invitation to advise.

The Court held that it could not reach a conclusion as to whether the use or threat of nuclear weapons would be lawful or unlawful according to international law.

After considering the relevant, applicable areas of international law (including article 6 of the International Covenant on Civil and Political Rights, article II of the Convention on the Prevention and Punishment of the Crime of Genocide, and international environmental law), the Court concluded that it would decide the question according to the law of armed force in the Charter of the United Nations and the law applicable in armed conflict. This law outlines elements which make the use of force legal, such as individual or collective self-defense if an armed attack occurs and when the Security Counsel decides to use force in accordance with Chapter VII of the Charter. But the Charter does not permit or prohibit any specific type of weapon in these allowed circumstances.

Article 51 of the U.N. Charter provides that self-defense is allowable only when it is proportional to the attack to which it is necessarily responding. For this reason, court theorized, but did not conclude, that nuclear self-defense may be out of proportion to any attack upon the responding state. Furthermore, Article 2, paragraph 4, of the Charter provides that if a specific use of force is illegal, the threat of that use of force is also illegal. Therefore, if a state were to threaten to use nuclear weapons in response to a non-reciprocal threat or attack, this threat would likely be considered illegal.

The court held that there are no explicit statements on the legality of the use or threat of nuclear weapons in international or treaty law, including the Second Hague Declaration of 1899, the Regulations annexed to the Hague Convention IV of 1907 or the 1925 Geneva Protocol. There have been many negotiations in decades prior, but no concrete prohibition through law, save for prohibitions on proliferation.

The Court held that international humanitarian law, despite being enacted prior to the advent of nuclear weapons, applies to the use or threat of nuclear weapons. The Court noted certain principles of this body of law, including the distinction between combatants and non-combatants and the requirement that nations use military weapons that are capable of distinguishing between the two.

The Court held that the use and threat of nuclear weapons seems irreconcilable to law applicable in armed conflict, but determined it could not reach a definitive conclusion on the matter.

The Court suggested that complete nuclear disarmament would be the best solution in settling the dispute over the use and threat of nuclear weapons. It advocated for good faith negotiation to achieve nuclear disarmament through a specific course of action.


President Bedajaoui noted that the lack of conclusion on the legality of the use or threat of nuclear weapons should not be a perceived as legal approval, but rather as a means of recording the legal uncertainty of the issue. Furthermore, he emphasized the destabilizing nature of nuclear weapons, which contradicts the purpose of humanitarian law. He also noted that it would be rash to conclude that a state’s survival (and thereby their use of a nuclear weapon) is a higher priority than the survival of humanity as a whole.

Judge Guillaume held that humanitarian concerns must be weighed against military requirements for protection, which could result in a valid reason for employing nuclear force. For example, nuclear weapons can be only be used lawfully in extreme cases of self-defense.

Judge Fleischhauer stated an appropriate time in which nuclear weapons could be used: “in an extreme case of individual or collective self-defence as the last resort of a State victim of an attack with nuclear, bacteriological or chemical weapons or otherwise threatening its very existence.” These are cases in which nuclear force is proportionate to the assault against the State employing nuclear force.


Judge Oda argued that the Court should have refrained from rendering an opinion due to the political motives inherent in the request. An advisory opinion, he contended, should only be given in the event of a real need.

Judge Weeramantry’s dissent stated that the use or threat of nuclear weapons is illegal in any circumstances. He noted the multitude of dangers inherent in the use or threat of nuclear weapons and held that international law is sufficient to establish the illegality of nuclear warfare.

Judge Koroma’s dissent stated that the use or threat of nuclear force would be a violation of international humanitarian law and therefore unlawful.

“The Court also points out that the prohibition of genocide would be pertinent in this case if the recourse to nuclear weapons did indeed entail the element of intent, towards a group as such, required by article II of the Convention on the Prevention and Punishment of the Crime of Genocide.” Page 96.

“The proportionality principle may thus not in itself exclude the use of nuclear weapons in self-defence in all circumstances. But at the same time, a use of force that is proportionate under the law of self-defence must, in order to be lawful, also meet the requirements of the law applicable in armed conflict, which comprise in particular the principles and rules of humanitarian law. And the Court notes that the very nature of all nuclear weapons and the profound risks associated therewith are further considerations to be borne in mind by States believing they can exercise a nuclear response in self-defence in accordance with the requirements of proportionality.” Page 96.

“President Bedjaoui considered that ’self-defence—if exercised under extreme circumstances in which the very survival of a state is in question—cannot engender a situation in which a State would exonerate itself from compliance with the ‘intransgressible’ norms of international humanitarian law.’ According to him, it would be very rash to accord, without any hesitation, a higher priority to the survival of a State than to the survival of humanity itself.” Page 99.

“The nuclear weapon caused death and destruction; induced cancers, leukaemia, keloids and related afflictions; causedgastrointestinal, cardiovascular and related afflictions; continued, for decades after its use, to induce the health-related problems mentioned above; damaged the environmental rights of future generations; caused congenital deformities, mental retardation and genetic damage; carried the potential to cause a nuclear winter; contaminated and destroyed the food chain; imperiled the ecosystem; produced lethal levels of heat and blast; produced radiation and radioactive: fallout; produced a disruptive electromagnetic pulse; produced social disintegration; imperiled all civilization; threatened human survival; wreaked cultural devastation; spanned a time range of thousands of years; threatened all life on the planet; irreversibly damaged the rights of future generations; exterminated civilian populations; damaged neighbouring States; and produced psychological stress and fear syndromes--as no other weapons do.” Page 102.