In the critical last two formal conclusions of its July 8, 1996 nuclear weapons advisory opinion, the International Court of Justice held as follows:

[Para. 105(2)]E. By seven votes to seven, by the President’s casting vote,

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;

In Favour: President Bedjaoui; Judges Ranjeva, Herczegh, Shi, Fleischhauer, Vereshchetin, Ferrari Bravo; Against: Vice-President Schwebel; Judges Oda, Guillaume, Shahabuddeen, Weeramantry, Koroma, Higgins.

F. Unanimously,

There exists an obligation to pursue in good faith and bring to a conclusion negotiations leading to nuclear disarmament in all its aspects under strict and effective international control.

In his seminal magisterial dissenting opinion of nearly 100 pages, Judge Weeramantry praised the many positive contributions of the Court's opinion, including its holding that threat or use of nuclear weapons is subject to the requirements of humanitarian and environment law, and its statement of the nuclear disarmament obligation in paragraph 2(F). But he firmly rejected the Court's equivocation regarding an extreme circumstance of self-defense involving the very survival of a state in paragraph 2(E). He stated at the outset of his dissent:

My considered opinion is that the use or threat of use of nuclear weapons is illegal in any circumstances whatsoever. It violates the fundamental principles of international law, and represents the very negation of the humanitarian concerns which underlie the structure of humanitarian law. It offends conventional law and, in particular, the Geneva Gas Protocol of 1925 [prohibiting the use of poisonous gases and analogous materials], and Article 23(a) of the Hague Regulations of 1907 [prohibiting the infliction of unnecessary suffering]. It

contradicts the fundamental principle of the dignity and worth of the human person on which all law depends. It endangers the human environment in a manner which threatens the entirety of life on the planet.

With regard to self-defense, Judge Weeramantry explained that the "undoubted right of the state that is attacked to use all the weaponry available to it for the purpose of repulsing the aggressor … holds only so long as such weapons do not violate the fundamental rules of warfare." "Once the domain of force is entered … the humanitarian laws of war take over and govern all who participate, assailant and victim alike."

The supremacy of humanitarian law applies as well, Judge Weeramantry emphasized, to the threat inherent in deterrence justified as a system of international security:

The threat of use of a weapon which contravenes the humanitarian laws of war does not cease to contravene those laws of war merely because the overwhelming terror it inspires has the psychological effect of deterring opponents. This Court cannot endorse a pattern of security that rests upon terror. In the dramatic language of Winston Churchill, speaking to the House of Commons in 1955, we would then have a situation where, "Safety will be the sturdy child of terror and survival the twin brother of annihilation." A global regime which makes safety the result of terror and can speak of survival and annihilation as twin alternatives makes peace and the human future dependent upon terror. This is not a basis for world order which this Court can endorse. This Court is committed to uphold the rule of law, not the rule of force or terror, and the humanitarian principles of the laws of war are a vital part of the international rule of law which this Court is charged to administer.

Judge Weeramantry’s dissent deserves to be widely circulated as a primer on the illegality of nuclear weapons. Replete with citations from the literature and jurisprudence of many cultures, he comprehensively discussed the facts and the law rendering nuclear weapons illegal in all aspects, patiently and convincingly rebutting every argument advanced by the nuclear weapon states. Addressing the argument that "collateral damage" caused by nuclear weapons targeted against military objectives is not prohibited, Judge Weeramantry stated that those who use nuclear weapons "cannot in any coherent legal system avoid legal responsibility" for the consequences, "any less than a man careering in a motor vehicle at a hundred and fifty kilometres per hour through a crowded market can avoid responsibility for the resulting deaths on the ground that he did not intend to kill the particular persons who died." While regretting that the Court’s opinion did not go the last mile, Judge Weeramantry began by stating that it "contains positive pronouncements of significant value" which "take the law far on the road towards total prohibition." If the history of law is the history of the progression from dissent to norm, Judge Weeramantry’s opinion could be a harbinger of things to come.

- John Burroughs, 8 March 2000