In 1994, the United Nations General Assembly asked the International Court of Justice to give an advisory opinion on whether the threat or use of nuclear weapons could ever be legal. The Court’s majority opinion in 1996 concluded that nuclear weapons would generally violate international law, but it did not declare an absolute prohibition. It left open the possibility that their use might be lawful in an extreme situation of self‐defence when a State’s very survival is at stake. Because of this, there was no definitive global legal control over nuclear weapons, and states could continue to develop and maintain them under the ambiguity of the judgment. This ambiguity has significant consequences. By allowing even the theoretical possibility that in a given specific situation, some states can possess nuclear weapons, the judgment fosters suspicion among nations. If the powerful states are allowed to maintain nuclear arsenals, other countries may ask: “If they can have them, why can’t we?” This logic can drive proliferation, undermine trust, and create justifications for interventions, conflicts, or arms races.
In this case, Sri Lankan jurist Justice CG Weeramantry delivered a powerful dissent. He argued that nuclear weapons are inherently illegal in all circumstances. He emphasized that their use or threat endangers present and future generations, violates humanitarian principles, and undermines the dignity of human life. Justice Weeramantry believed that international law must protect humanity, not serve the interests of powerful states. His moral courage, however, came at a personal cost: according to his autobiography and accounts of his career, his dissent likely contributed to his failure to be reappointed to the ICJ after serving as Vice-President.
A proud son of Sri Lanka, Justice Weeramantry drew on his nation’s long traditions of peace, law, and philosophical wisdom to shape his understanding of international law. His thinking shows that even a country with modest geopolitical power can produce visionaries whose principles and moral courage influence the world. His legal and ethical insights on nuclear weapons continue to guide global discussions, reminding humanity of the importance of justice, fairness, and the protection of life for future generations.
Today, as tensions over Iran’s nuclear program continue, the ambiguity left by the ICJ majority judgment remains highly relevant. By not declaring nuclear weapons illegal under all circumstances, the Court unintentionally allowed states to maintain or develop arsenals under the pretext of extreme self‐defence. This loophole contributes to mistrust and creates incentives for countries that prefer to pursue nuclear capabilities, fearing regional imbalance or coercion by nuclear-armed states.
Justice Weeramantry’s dissent offers a guide for what could have been done differently. Had the international community acted on the principle that nuclear weapons are inherently illegal and illegitimate for any state, and applied this principle consistently, the political and strategic pressures that drive proliferation might have been significantly reduced.
Stronger enforcement of non‐proliferation norms, coupled with transparent verification mechanisms and equal treatment of all states, could have prevented countries from feeling the need to develop its nuclear program. Moreover, a strict and universally enforced prohibition on the proliferation of nuclear weapons could have reduced the justification for interventions or wars framed around the fear of other countries developing nuclear capabilities.
