THE TREATY ON THE PROHIBITION OF NUCLEAR WEAPONS (TPNW) AND CUSTOMARY INTERNATIONAL LAW
The Treaty on the Prohibition of Nuclear Weapons (TPNW) reached the required number of 50 ratifications. Accordingly, it will enter into force on January 22 2021.The Treaty will reinforce the multilateral regime of non-proliferation of nuclear weapons and provide a path for their elimination. Additional ratifications are expected in the next few months.
The TPNW bans developing, testing, producing and manufacturing nuclear weapons and other nuclear explosive devices as well as in any other way acquiring, possessing of stockpiling them. Prior to their ratification other signatories accept the obligation to refrain from acts contrary to its objective and purposes. Thus, in practice, over one third of the membership of the United Nations are already bound, one way or another, by the Prohibition Treaty.
Five States among the 189 Parties to the Treaty on the Non-proliferation of Nuclear Weapons (NPT) are recognized as “nuclear-weapon States” and have undertaken to “pursue negotiations in good faith on effective measures relating to the cessation of the nuclear arms race at an early date and to nuclear disarmament”. Until to-day, 50 years after the entry into force of the NPT, such negotiations have not even started.
The nuclear armed countries have stated in more than one occasion their opposition to the TPNW and chose not to participate in the Open Ended Working Group (OEWG) established by the United Nations to “take forward multilateral disarmament negotiations”. Some of their allies, however, were involved in the activities of the Working Group and among them only the Netherlands took part in the actual negotiation of the TPNW, which was adopted on July 7 2017 and opened to the signature of States on September 20 of the same year. Brazil was the first State to sign and its ratification process is under exam in the National Congress.
The Parties to the TPNW and the supporters of the Treaty acknowledge that it will not immediately bring about the the elimination of nuclear weapons. For this to happen the participation of the nuclear-weapon possessors is obviously necessary. Under Articles 1 and 2 of the TPNW the States that accede to it must present to the Secretary General of the United Nations, within 30 days after the entry into force of the Treaty for them, a declaration stating that they did not possess or controlled nuclear weapons or nuclear explosive devices prior to that date. They must also declare whether there are in their territories such weapons or devices owned, possessed or controlled by another State. In that case, acceding States accept the obligation to immediately remove them from operational status and to destroy them under verification according to a legally binding and time-defined elimination program.
Upon the adoption of the TPNW the five countries recognized by the NPT as nuclear-weapon States put forth a joint declaration stating, inter alia, that the Treaty “risks undermining the existing international security architecture which contributes to the maintenance of international peace and security”. On September 20 2017 NATO issued the following press release: “Seeking to ban nuclear weapons through a treaty that will not engage any state actually possessing nuclear weapons will not be effective, will not reduce nuclear arsenals, and will neither enhance any country’s security nor international peace and stability. Indeed it risks doing the opposite by creating divisions and divergences at a time when a unified approach to proliferation and security threats is required more than ever."
The TPNW is not aimed at specific States and seeks primarily to delegitimize the possession and use of nuclear weapons. Its members believe that the elimination of such weapons will bring security to all and enhance world peace. Longstanding divergences about the ways to confront the nuclear threat were not caused by the TPNW, but instead resulted from the discriminatory division of the world into two categories of nations: the nuclear armed and all the others, established by the NPT in 1970.
Also on July 7 2017 three nuclear-weapon States – United States, France and United Kingdom – formally declared that they did not intend to sign, ratify or ever to join the TPNW. Accordingly, they went on, “there will be no change in the legal obligations on our countries with respect to nuclear weapons. For example, we would not accept any claim that this treaty reflects or in any way contributes to the development of customary international law”.
The mere fact that those three countries felt necessary to deny formally and jointly the existence of a norm of customary law against the possession and use of nuclear weapons demonstrates the relevance of the TPNW. Were it evident for everyone that this instrument has no impact whatsoever on the legality of such weapons, there would be no need to point out so emphatically the absence of a customary norm and the very possibility of its future evolution. What the nuclearly armed countries in fact fear is the generalization of the rejection of nuclear weapons expressed in the TPNW and its becoming practice and opinio juris.
As indicated above, Article 38, 1. b), of the Statute of the International Court of Justice (ICJ) establishes that “The Court, whose function is to decide in accordance with international law such disputes as are submitted to it, shal apply: a) international conventions, whether general or particular, establishing rules expressly recognized by the contesting states;b) international custom, as evidence of a general practice accepted as law; c) the general principles of law recognized by civilized nations”.
The preventive character of the pronouncements quoted above becomes thus quite clear. For the TPNW to be considered a source of customary international law both elements established by the ICJ would be lacking: “express recognition” and “general practice”. By declaring their objection at the moment of the formation of the norm, those that reject it defined themselves as “persistent objectors” and thus would not consider thenselves subject to it even if the norm later becomes customary. The posture of persistent objection is recognized by the jurisprudence of the ICJ and by the International Law Commission of the United Nations.
Nevertheless, several important features of the TPNW recommend it to the universal conscience. Its worth is not simply symbolic nor is it a mere reiteration of commitments already legally undertaken, to the extent that it reinforces such commitments and creates obligations not contemplated in the NPT and other instruments in the field of disarmament. The TPNW also forbids its Parties to encourage others to carry out prohibited activities and demands an active attitude of stimulus to other States to adhere to it (Art. 12). It may be argued that a member of NATO would not the forbidden to join the TPNW in case it declines to participate in the nuclear dimension of the alliance. In fact, not all members of NATO allow the use of their territories for the emplacement of nuclear weapons. The compatibility between the NPT and the emplacement of nuclear weapons in the territory of some members of that alliance has been the subject of doubts and occasionally also of accusations of non-compliance with obligations assumed under Article I of that instrument.
Contrary to what some adversaries of the TPNW would like us to believe, its impact will not be felt only in Western democratic countries, where the weight of public opinion is more visible than elsewhere. International law is applicable to all States, regardless of their political systems, and internal pressures do not stem only from civil society: they also come from other countries and from public statements and private demarches, from international organizations, from positions taken by eminent personalities as well as from the universal conscience. Support by world public opinion to effective measures of elimination of nuclear weapons will certainly grow as the frustration with the fast pace of the arms race and lack of concrete progress also increase.
It is obvious that TPNW will not immediately become a norm of international law recognized and respected by all. Under Article 12 its Parties committed to encourage those that are not yet parties to sign and ratify, and the non-govermental organization known as ICAN has taken upon itself the task of clarifying issues related to the TPNW in demarches before other governments as part of a drive to secure new signatures and ratifications.
It is hard to argue a legal incompatibility between the NPT and the TPNW. The latter is in fact a logical consequence of the provisions of Article VI of the former, which allow each State Party to promote disarmament negotiations. The TPNW strengthens fidelity to the NPT. A decision to abandon the NPT could not be ascribed exclusively, or even mainly, to the advent of the TPNW.
The controversy around the TPNW is due to disagreement over the most effective way of dealing with the problem of the existence of nuclear weapons without compromising the security of any State and of the world at large. The NPT is supported by those that give priority to non-proliferation, while the promoters of the TPNW represent the belief that 75 years after the invention of the nuclear weapon and 50 since the advent of the NPT concrete progress in disarmament is needed to prevent lack of faith in and the unraveling of the current legal regime. The TPNW is a challenge to the existing legal order but this does make it incompatible with the main instrument that codifies that order. Article VI of the NPT points directly to nuclear disarmament “at an early date”. It should not be used to maintain a status quo that perpetuates insecurity for all.
The Parties to the TPNW and the supporting organizations have a duty to demonstrate to the nuclear armed States that the international community as a whole has a special interest in its universalization. All States have a high moral, ethical and legal responsibility to do whatever is at their reach to prevent a nuclear catastrophe in which there will be no victors – only losers.
Brazilian Ambassador, former UN High Representative for Disarmament Affairs
President of Pugwash
Conferences on Science and World Affairs
 Besides the 50 States that already ratified, 34 others have signed the Treaty so far.
 Article 38 (b) of the 1969 Vienna Convention on the Law of Treaties.
 All 193 Member States of the United Nations are also Party to the NPT, except four, DPRJ, India, Israel and Pakistan.
 China, United States, France, Russia and United Kingdom.
 NPT Article VI.
 In an Advisory Opinion issued in 1996 at the request f the UN General Assembly the International Court of Justice stated that “There 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". It must be acknowledged that over the decades the two main possessors of nuclear weapons have managd do agree on significant reductions in the size of their arsenals. However, technological advances have greatly increased the accuracy and destructive power of their means of destruction. Moreover, such bilateral negotiations were not organically linked to the norm contained in Article VI of the NPT.
 See UNGA Resolutions 67/56 (2012), 68/46 (2013), 69/41 (2014) and 70/33 (2015) and especially 71/258, of December 13 2016.
 The result of the vote at the negotiating Conference was 122 in favor, one against (Netherlands) and one abstention (Singapore).
 The possessors of nuclear weapons vow to keep them “as long as nuclear weapons exist”, a self-serving expression to justify exclusive and permanent possession
 For instance, the prohibition to carry out tests with nuclear explosives is expressed in the Comprehensive Test-ban Treaty (CTBT), although this instrument is not yet in force, and in other international texts.
 Among those, the non stationing of nuclear weapons in the territories of third States (Art. 1(g) and assistance to victims of nuclear explosions (Art. 6).
 Nuclear weapons are stationed today in the territories of Belgium, Germany, Italy, Netherlands and Turkey.
 “Each nuclear-weapon State Party to the Treaty undertakes not to transfer to any recipient whatsoever nuclear weapons or other nuclear explosive devices or control over such weapons or explosive devices directly, or indirectly […]”.
 ICAN (international Campaign to Abolish Nuclear Weapons) is a coalition of non-govrnmental organizations thatpromote adherence to the TPNW and its implementation. ICAN was awarded the 2017 Nobel Peace Prize for its active participation in the promotion and negotiation of the TPNW
 The first resolution of the UM General Asembly in January 1946 created a Commission “to deal with the problems raised by the discovery of nuclear energy” and to present proposals for the elimination of nuclear weapons. The rivalry between the two superpowers of the time prevented any progress and the Comission wasfinally disbanded