There is no comprehensive or universal ban in international law on the use of nuclear weapons. However, in July 1996 the International Court of Justice concluded that international humanitarian law did apply to the use of nuclear weapons and that their use would generally be contrary to IHL’s principles and rules.
Since the first and only use of nuclear weapons in 1945, the international community has wrestled with the issue of how the law of war applies to such weapons.
The destructive power of nuclear weapons puts them in a category of their own. The dropping of nuclear bombs on two Japanese cities in 1945 caused massive loss of life. The radiation that was generated covered a wider area affecting public health, agriculture, natural resources and infrastructure for years to come. Today’s nuclear weapons are many times more powerful.
Since the end of World War II the ICRC has held the view that it is difficult to envisage how the use of nuclear weapons could be compatible with the principles and rules of international humanitarian law. But no specific ban has ever been adopted by States. Neither the 1949 Geneva Conventions, nor the adoption of two Additional Protocols in 1977, make direct reference to the legality of nuclear weapons.
States have dealt with the threat of nuclear weapons in other ways, in particular through the Treaty on non-proliferation. But in 1996 the legality issue was addressed again, this time in an advisory opinion of the International Court of Justice, requested by the UN General Assembly, on whether “the threat or use of nuclear weapons is in any circumstances permitted under international law”.
The Court found that the limitations imposed by international law on the means and methods of waging war applied to nuclear weapons. It set out the fundamental principles of IHL, in particular the requirement to distinguish between combatants and non-combatants, the ban on targeting civilians, and the prohibition of weapons that, by their nature, cannot distinguish between civilian and military targets, or that cause superfluous injury or unnecessary suffering to combatants.
The Court said that these principles had to be upheld by all States, regardless of whether they had ratified the relevant treaties, since they were “intransgressible principles of international customary law”.
While the Court found that the use of nuclear weapons seemed “scarcely reconcilable” with respect for humanitarian law, it declared 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 ICRC welcomed the Court’s unequivocal reaffirmation of the principles and rules of IHL as applied to the use of nuclear weapons. In 2002 it refined its own position in the light of the Court’s opinion.
The position reaffirms that “the principles of distinction and proportionality and the prohibition on causing superfluous injury or unnecessary suffering, apply to the use of nuclear weapons”.
In view of the unique characteristics of nuclear weapons the ICRC further calls on all States not to use nuclear weapons, irrespective of whether they considered them legal or not, to take measures to limit the risk of proliferation and to pursue negotiations on a complete ban on nuclear weapons and their elimination.