The present study was mandated by the 26th International Conference of the Red Cross and Red Crescent in December 1995. A year earlier, the UN General Assembly had asked the International Court of Justice for an advisory opinion on the following question: “Is the threat or use of nuclear weapons in any circumstance permitted under international law?”
All States wishing to do so had the opportunity to express their opinion on this question, in written statements and the oral pleadings before the Court. In an advisory opinion of 8 July 1996, the International Court of Justice stated in relation to customary international law and the applicability of international humanitarian law to nuclear weapons that:
There is in neither customary nor conventional international law any specific authorization of the threat or use of nuclear weapons;
There is in neither customary nor conventional international law any comprehensive and universal prohibition of the threat or use of nuclear weapons as such;
A threat or use of nuclear weapons should also be compatible with the requirements of the international law applicable in armed conflict, particularly those of the principles and rules of international humanitarian law, as well as with specific obligations under treaties and other undertakings which expressly deal with nuclear weapons;
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;
However, in view of the current state of international law, and of the elements of fact at its disposal, the Court cannot conclude definitively whether the threat or use of nuclear weapons would be lawful or unlawful in an extreme circumstance of self-defence, in which the very survival of a State would be at stake.
As mentioned above, this opinion took into account a wide range of legal analysis and scientific evidence presented by States. As a result, the Court being the principal judicial organ of the United Nations, the ICRC had to take due note of the Court’s opinion and deemed it not appropriate to engage in a similar exercise at virtually the same time.