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Thirty years ago, on 8 July 1996, the International Court of Justice (ICJ) – the principal judicial organ of the United Nations – issued a landmark advisory opinion on the legality of the threat or use of nuclear weapons. It followed a major civil society campaign involving the collection of millions of petition signatures from concerned citizens across the world.
The court concluded, unanimously, that “[t]here 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”.
However, it was split on the question of whether the use or threat of use of nuclear weapons would be unlawful in all circumstances. By seven votes to seven, with the president’s casting vote, the court concluded that “the 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”.
It could not definitively conclude, however, “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 dissenting opinions, a number of the judges on the court argued that the use of nuclear weapons would be unlawful in all circumstances.
To consider the legacy of this historic ICJ advisory opinion, Lex Mundi Nova (a project of Horizon 2045) organised a webinar series in partnership with the International Campaign to Abolish Nuclear Weapons (ICAN) and others, involving leading experts from various fields.
They examined the ruling itself, the shifts in international law and new science in the last three decades, and emerging technological and geopolitical risks – from nuclear testing to artificial intelligence to warfare in space – and discussed whether the ruling’s ambiguities and gaps could be resolved in the light of today’s legal and evidentiary realities.
The most significant legal development in the field of nuclear weapons since the court’s historic ruling is the adoption of the Treaty on the Prohibition of Nuclear Weapons (TPNW) in 2017 and its entry into force in 2021. This landmark UN treaty prohibits a wide range of activities relating to nuclear weapons, including their use and threatened use.
As reflected in the TPNW’s preamble, the states parties consider “that any use of nuclear weapons would be contrary to the rules of international law applicable in armed conflict, in particular the principles and rules of international humanitarian law”. To date, just over half of the world’s states have accepted legal obligations under the TPNW either as parties or signatories.
Marking the anniversary of the ICJ’s advisory opinion on nuclear weapons, Melissa Parke, the executive director of ICAN, said:
“Thirty years ago, the highest judicial body in the world concluded that there is an obligation under international law to negotiate for – and achieve – nuclear disarmament. But instead of pursuing this objective in good faith nuclear-armed states have moved in the opposite direction, placing all of humanity in even greater danger. As we reflect on the legacy of the court’s historic ruling, let us consider how we might make use of the international legal system in the years ahead to advance the cause of a nuclear-weapon-free world. International law matters more than ever; it must be defended and promoted as if our lives depend on it – because they do.”
Christopher Weeramantry (right), a judge of the International Court of Justice from 1991 to 2000, spoke at the launch of the International Campaign to Abolish Nuclear Weapons (ICAN) in Melbourne, Australia, in 2006 and at subsequent ICAN events. He issued a dissenting opinion in 1996 arguing that the use of nuclear weapons is illegal in all circumstances. Credit: Adam Dempsey
Main image: Disarmament campaigners outside the International Court of Justice in The Hague in July 1996. Credit: Martin Dunkerton