ABSTRACT
Nuclear weapons, always immoral, also became illegal on 22 January 2021 when the Treaty on the Prohibition of Nuclear Weapons (TPNW) entered into force. States other than major nuclear powers forced through an instrument of international humanitarian law against the will of all major powers and most Western countries. The TPNW builds on the World Court’s 1996 Advisory Opinion to establish a new normative settling point on the ethics, legality and legitimacy of the bomb. Unlike the Non-Proliferation Treaty, which embedded the geopolitical priorities of the nuclear weapon states, the TPNW reflects the preferences of the majority of states in a polycentric 21st century. It prohibits the possession of nuclear weapons; the use and threat of use of nuclear weapons, thereby delegitimising the doctrine and practice of nuclear deterrence; nuclear testing; and the hosting of nuclear weapons. While the TPNW is legally binding only for signatories, it has been deployed by supporter states and civil society advocates as evidence of a new global political norm against possession. The nuclear-armed states need to rejoin the global mainstream on nuclear policy and work collectively to implement practical and credible measures towards nuclear risk reduction and disarmament, while holding fast to non-proliferation.
