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  :: Treaties International Court of Justice, Legality of Nuclear Weapons, October 30, 1997

Legality of Nuclear Weapons

International law regarding nuclear weapons comprises a mix of:
a) specific agreements and treaties on nuclear weapons (see treaties and agreements section 3).
b) treaties and customary law relating to international peace and security, humanitarian laws of warfare and human rights law. This includes, inter alia, the United Nations Charter, Hague Conventions, Geneva Conventions, Nuremberg Principles and Genocide Convention.
c) judicial decisions and qualified teachings.

The most authoritative consideration of international law as it relates to nuclear weapons is given in the 1996 Advisory Opinion of the International Court of Justice on the Legality of the Threat or Use of Nuclear Weapons (Appendix I). The court applied treaty law and customary law to determine that the threat or use of nuclear weapons is generally illegal and that there is an obligation to conclude negotiations on complete nuclear disarmament. The conclusion on illegality of threat or use was based predominantly on the principles of humanitarian law under which it is prohibited to use weapons or methods of warfare which:

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See Also
International Court of Justice Opinion on the Legality of the Use by a State of Nuclear Weapons in Armed Conflict 
Full Opinion 

are directed against civilians or cannot discriminate between military targets and civilians
cause unnecessary suffering to combatants
are disproportionate to the act to which is being responded violate the territory of neutral states
cause long-term and widespread damage to the environment
use poisonous substances.

The Court's decision was controversial in that it concluded that the threat or use of nuclear weapons was generally illegal, but did not rule out the threat or use in all circumstances. The Court left a cloud of uncertainty over "an extreme circumstance of self-defence, in which the very survival of a State would be at stake." Even in this circumstance the Court affirmed that humanitarian law applies, and did not accept the NWS arguments that threat or use in this instance would be legitimate. Neither did the Court accept the NWS arguments that the use of small, precisely targeted tactical nuclear weapons would conform to international law.

The conclusion on the disarmament obligation arose predominantly from the Non Proliferation Treaty. However, ICJ President Bedjaoui noted that this disarmament obligation had achieved the status of a customary obligation thus applying to all states including those not members of the NPT.

During the negotiations on the Statute for an International Criminal Court, several countries sought to include the threat or use of nuclear weapons as a crime which would come under the jurisdiction of the Court. They argued that the ICJ had determined that the threat or use of nuclear weapons was generally incompatible with international law including the humanitarian laws of warfare, and that any threat or use would thus be a war crime or crime against the peace. The NWS, and some of their allies, opposed this, and in order to obtain their support, the threat or use of nuclear weapons was not specifically included as a crime under the jurisdiction of ICC in the agreed statute. However, New Zealand, on ratification, noted that the war crimes provision of the ICC Statute would apply to the threat or use of nuclear weapons including in situations where such threat or use was by a state in self-defence (Appendix II).

Compliance and enforcement
There has been a high level of compliance by non-nuclear weapon states with their obligations under the Non-Proliferation Treaty not to acquire nuclear weapons. A number of countries including Egypt, Canada, Sweden, Germany, Japan, Switzerland and Australia were supposedly considering the development of nuclear weapons prior to joining the NPT and others including Brazil, Argentina, South Africa, Ukraine, Kazakhstan and Belarus either had nuclear weapons or were engaged in nuclear weapons programs which they abandoned on joining the NPT.

The Security Council, which operates as the enforcing body for international law, has taken action to prevent the proliferation of nuclear weapons in some instances - particularly with respect to North Korea, Iraq, Pakistan and India. However, it has not acted to ensure compliance by the nuclear weapon states with their obligations to conclude negotiations on complete nuclear disarmament, nor to limit their policies on threat and use of nuclear weapons to those compatible with international law. The NWS, for instance, continue to test and modernise nuclear weapons, maintain nuclear weapons on alert status and maintain policies including the threat to use nuclear weapons in a wide variety of circumstances.

UN Under-Secretary General Jayantha Dhanapala notes that compliance with nuclear disarmament law is very weak, partly because there is a lack of compliance and enforcement mechanisms, and partly because the "lack of congruency between - on the one hand -- the solemn commitments by the nuclear-weapon states to global nuclear disarmament and - on the other hand - the tendency of such states to continue to refer to such weapons as "vital" or "essential" to their security."

Domestic and regional implications
The 1996 ICJ Advisory Opinion gives additional legal weight to states and inter-state organisations wishing to prohibit nuclear weapons within their regions and domestic jurisdictions. Some States have already adopted legislation prohibiting nuclear weapons from their territory. Judge Weeramantry, former Vice-President of the ICJ, has argued that States could now, if they wish, go further and prohibit the transit of deployed nuclear weapons through their territorial waters and Exclusive Economic Zones. In April 2001 the Inter-Parliamentary Union adopted a resolution without dissent calling on States to prohibit the transit of all weapons of mass destruction including nuclear weapons through their EEZs.

States could also adopt legislation making it a criminal act to possess, develop, control, use or threaten to use nuclear weapons, regardless of whether that act occurred within their territory or was extra-territorial.

Disarmament, Non-Proliferation, and the Rule of Law, Jayantha Dhanapala, UN Under-Secretary-General for Disarmament Affairs
Advisory Opinion on the Legality of the Threat or Use of Nuclear Weapons, International Court of Justice, 1996
The Legality of Threat or Use of Nuclear Weapons: A Guide to the Historic Opinion of the International Court of Justice,
John Burroughs Lit Verlag, Muenster, 1997 www.lcnp.org/wcourt/Adlegality.htm
Bombs Away? The World Court Decision on Nuclear Weapons. Disarmament Diplomacy, No.8, September (1996). www.lcnp.org/wcourt/Bombs%20away.htm
An Open Letter on Trident and Nuremberg, Commander Robert Green, Royal Navy (Retired) www.lcnp.org/wcourt/tridentnuremburgltr.htm

Prepared by Alyn Ware, coordinator of the Parliamentary Network for Nuclear Disarmament, a project of the Middle Powers Initiative