Nuclear Powers' Disarmament Obligation under the Treaty on the Non-Proliferation of Nuclear Weapons and the Comprehensive Nuclear Test Ban Treaty: Interactions between Soft Law and Hard Law

The Comprehensive Nuclear Test Ban Treaty (CTBT) will not be effective until all the 44 states listed in its Annex 2 ratify it. A special link has been established between the Treaty on the Non-Proliferation of Nuclear Weapons (NPT) and the CTBT. The disarmament obligation set by Article VI of the NPT, which has not yet been complied with, remains highly controversial. The relevant subsequent practice of the states parties to the NPT shows that the ratification of the CTBT is to be considered the first of the practical steps towards compliance with Article VI. However, as the practical steps do not set any legally binding norms, there is no legal obligation to ratify the CTBT, not even for the 44 states listed in Annex 2 whose ratification is essential. The paper deals with the position of nuclear powers party to the NPT that have not yet ratified the CTBT (most prominently the US and China) and demonstrates that these states should at least provide detailed motivation for their conduct. Otherwise, other states parties to the NPT could consider them as not complying in good faith with Article VI of the NPT and invoke the inadimplenti non est ademplendum rule to justify breaches of their own obligations under the same treaty.