The success of any arms control treaty generally depends on its ability to achieve its primary objectives and intended outcomes. At the heart of measuring such success are effective compliance criteria and verification mechanisms. This includes the ability to apply metrics to assess tangible outcomes and measurable outputs and benchmarks of achievement, including on-site visits. In relation to nuclear issues, this also means that verification of both the non-diversion of nuclear material from declared peaceful activities (i.e., correctness of conduct), and the absence of undeclared or clandestine nuclear activities in a particular state (i.e., completeness in following treaty terms).

The TPNW was welcomed at the UN General Assembly, under the participation of a wide range of humanitarian groups and civil society organizations, supported by a groundswell of nations around the world. The Treaty firmly implants new law into the international legal landscape for states who wish to ratify it, sowing the seeds of potentially new normative behavior within the global community more generally. Indeed, the TPNW purports to strive for universality, raising significant questions regarding its ambitions in achieving legal unity within the wider international legal order. The dedication to the spirit of the Treaty cannot be ignored, nor can the optimism to ban nuclear weapons.

The adoption of the Treaty on the Prohibition of Nuclear Weapons (TPNW) at the United Nations General Assembly and its movement toward ratification raises both hopes amongst some and fears amongst others regarding the development of customary practice under international law. Although the TPNW purports to strive for universality, significant questions remain regarding the Treaty’s aims and achieving legal unity within the international legal order. The purpose of this chapter is to explore these and other issues regarding the TPNW’s prospects of achieving universality under customary international law and opinio juris.

One of the fundamental problems with the TPNW is that the five officially recognized nuclear-weapons states – Russia, the United States, China, France and the United Kingdom, collectively the NWS – and four other states who possess nuclear weapons – India, Pakistan, Israel and North Korea – have boycotted the Treaty negotiations and refused to sign or ratify it. Despite moves toward neo-universalism, this leaves an important gap in the TPNW legal framework, because it does not directly bind the NWS and it seems unlikely that these NWS will join the Treaty or be bound under opinio juris. One way to remedy this problem and fill the legal gap is to appeal to an existing set of legal obligations found in international jurisprudence to which NWS are already bound. Specifically, the International Court of Justice (ICJ) has highlighted that states owe obligations erga omnes – toward all – that derive from other international laws, legal principles and conventions.

Civil society organizations and proponents of disarmament feel they are on the right side of history and morality in advocating for the elimination of nuclear weapons. They see growing support on a global scale to ban the testing and use of nuclear weapons or explosive devices under any circumstances. As this movement gains traction, supporters of the TPNW are mobilizing to hasten the pace of nuclear abolition in an absolutist form. They are actively working to change how individuals and states view nuclear weapons with the ultimate goal of universal disarmament through an active campaign of stigmatization and delegitimization.

Although disarmament is required under Article VI of the NPT, there seems to be little movement toward this end. Indeed, a recent review of various nuclear defense doctrines in nuclear-armed states reveals the opposite, with clear evidence of nuclear renewal policies, raising questions amid mounting humanitarian pressures and developments. In an attempt to move disarmament efforts forward, the Marshall Islands raised vital questions in the International Court of Justice regarding long-standing questions on disarmament and negotiations toward a treaty to cease the arms race pursuant to Article VI of the NPT.

A legacy of the Cold War is that nuclear arms protect nations from attack; a stance that supporters of the TPNW wish to change. Indeed, this author would contend that nuclear weapons do not protect nations but actually threaten national, regional and global security. Many advocates of nuclear disarmament believe that the TPNW marks a new beginning; it was even celebrated with the Norwegian Nobel Peace Prize awarded to the International Campaign to Abolish Nuclear Weapons (ICAN), at the time, a relatively newly formed civil society organization. The TPNW demonstrates international support to take decisive action to eliminate nuclear weapons and the threat they pose to international peace and security.

The text of the TPNW was agreed during a relatively short negotiation period. It includes comprehensive prohibitions regarding participation in any nuclear weapon activities, including undertakings not to develop, test, produce, acquire, possess, stockpile, use or threaten to use nuclear weapons. The Treaty prohibits the deployment of nuclear weapons on national territory and requires states parties to prevent and suppress any prohibited activity by persons within or on their territory or under their jurisdiction or control.

Advocates of the Treaty on the Prohibition of Nuclear Weapons (TPNW) invariably view nuclear weapons as a threat to international peace and security. The ideals presented by the humanitarian disarmament movement challenge conventional nuclear deterrence policies and defense doctrines currently held by the nuclear-weapon states and their allies. An aim of the TPNW is to challenge basic deterrence assumptions with the intention of advancing normative change by delegitimizing nuclear weapons and changing how they are perceived throughout the world. The position of some states that nuclear weapons provide a military deterrence for overall global security and protection against war is under increasing scrutiny and now there is an actual treaty – the TPNW – opposing this position.

Nothing about developing and implementing a treaty on the prohibition of nuclear weapons is easy. While supporters of the TPNW undoubtedly claim a victory in its coming into being, its opponents note its shortcomings warning of the adverse and dire consequences. The degree to which such concerns will materialize remains to be seen. What is certain, however, is that the adoption of the TPNW has marked the beginning of a new schism in the international community. The word schism is appropriate in this context, loosely defined as “a split or division between strongly opposed sections or parties, caused by differences in opinion or belief.”

The TPNW represents an unprecedented departure from current practice in that it is the first multilateral treaty to ban nuclear weapons. It is supported by 122 nations, representing a sizable contingent of the world’s population spanning various geographical divides. Although not celebrated by all nations, and vehemently opposed by nuclear-weapon states, its adoption at the UN General Assembly in July 2017 marks a fundamental departure from the status quo regarding armament matters. The primary purpose of this book was to examine the TPNW within the broader legal, diplomatic and political context in relation to the existing nuclear nonproliferation and disarmament framework in international law, exploring the influence of the Treaty from various perspectives and its potential impact on the nuclear architecture as it stands today.

The TPNW demonstrates growing support of humanitarian efforts to take action against nuclear weapons. It marks a fundamental shift by some states and individuals in the international community in their approach to addressing concerns regarding nuclear weapons and represents their willingness to challenge the status quo regarding the power of the nuclear states and their allies. Humanitarian disarmament efforts through civil society groups, in conjunction with a core group of like-minded states, have rallied together to outlaw nuclear weapons. The intention is to relegate them to the annals of history – eliminating them forever.

The Treaty on the Prohibition of Nuclear Weapons 2017 marks an important development in nuclear arms control law, diplomacy and relations between states. Adopted by the UN General Assembly on July 7, 2017, it was supported by 122 nations, representing a potential disruptor to the nuclear status quo. It is the first treaty to ban nuclear weapons outright, taking a clear humanitarian approach to disarmament. Despite its success in coming to fruition, however, it is not celebrated by all nations. The permanent members of the UN Security Council neither participated in its negotiations, nor adopted the final text. No state with nuclear weapons endorses the Treaty and indeed they openly oppose its very existence.