In 2014, the Republic of the Marshall Islands (RMI) made applications against nine states who allegedly possess nuclear weapons at the International Court of Justice (ICJ), suggesting those countries failed to fulfill their Article VI obligations under the Treaty on the Non-proliferation Proliferation of Nuclear Weapons (NPT). The ICJ dismissed all the cases it heard. While a disappointing result for disarmament advocates, this episode has had a lasting impact on international law, and raises several policy questions for disarmament initiatives, especially the Treaty on the Prohibition of Nuclear Weapons (TPNW). By raising the threshold for what qualifies as a legal dispute, these decisions suggest disarmament proponents might need to reflect on how they frame the relationship between the TPNW and the NPT, and to consider whether they use international arbitration to achieve their goals. Background The RMI v. UK case provides important lessons because it was only one heard against an NPT signatory. The RMI claimed the NPT has become customary international law and is, therefore, binding on all states regardless of their NPT signature.1 The RMI v. UK case, dismissed after a tiebreaking vote by the ICJ president, introduced a new “awareness criterion” for what qualifies as a legal dispute.2 Before this decision, the relevant case law on the definition of a legal dispute allowed for some flexibility in the substance and form of the evidence. Inter alia, a legal dispute was a “disagreement on a point of law or fact, a conflict of legal views of interests”; or when “the claim of one party is positively opposed by the other.” The ICJ could draw on a wide range of sources to make an “objective determination” about whether a dispute existed.3 In the RMI v. UK case dismissal, however, the ICJ added an additional requirement to its definition of what constitutes a legal dispute: “a dispute exists when it is demonstrated, on the basis of the evidence, that the respondent was aware, or could not have been unaware, that its views were ‘positively opposed’ by the applicant.”4 Notwithstanding the abstract question of how to ascribe consciousness and awareness to a state, this criterion was based on a misinterpretation of previous case law, as noted by one dissenting opinion.5 The quoted derived its language from a previous case, in which it was articulated as a statement of fact that given the evidence one country could not have been unaware of another’s complaints.6 This statement of fact was elevated to a new legal requirement in the RMI v. UK case. The ICJ elaborated on the awareness criteria in its rejection of the RMI’s evidence. First, the court stated that the respondent must be present when the complaint is made.7 Second, the applicant has to be specific about the alleged breach of obligation and the breach’s legal source. The RMI’s statement at the High-Level Meeting of the General Assembly on Nuclear Disarmament was rejected on these grounds, despite the United Kingdom being present at the meeting. Legal Implications of the TPNW Much evidence suggests the TPNW has precipitated a new legal dispute. First, there appear to be positively opposed views on the TPNW between nuclear-weapon states (NWS) and TPNW proponents. States diverge on whether participating in TPNW negotiations fulfills NPT obligations. For instance, the United States, Russia, France, and the United Kingdom released a joint statement after the TPNW text was finalized claiming that there will “be no change in the legal obligations on our countries with respect to nuclear weapons” and signaling that they “do not intend to sign, ratify or ever become party to it.” They see this behavior as in line with their “continued commitment to the NPT.”8 On the other hand, TPNW proponents such as Austria and Ireland frame it as “perfectly consistent with the NPT.”9 Similarly, TPNW proponents argue that the ban treaty contributes toward “the implementation of Art VI of the NPT.”10 They explicitly link the TPNW to NPT obligations. Furthermore, these statements from TPNW proponents occurred at the First Committee meeting, which nuclear-armed states attended – fulfilling the attendance element of the new legal dispute criteria. Policy Impact The existence of a legal dispute leads to two policy questions. First, should TPNW proponents reiterate the linkage between the TPNW and Article VI of the NPT in NPT Preparatory Committees and Review Conferences? Doing so could risk paralyzing the already fraught process in the NPT disarmament working group – a result NWS would likely blame on ban treaty proponents. Second, is it advisable to initiate new legal proceedings, despite having the legal standing to do so? Indeed, the ICJ has demonstrated yet again that it is reluctant to make definitive rulings on sensitive issues such as disarmament.11 In RMI v. UK, they established a new and harsher threshold for a legal dispute that will affect all future cases. In fact, the principle is already in international law textbooks.12 The ICJ does not seem to be an appropriate forum for pursuing disarmament objectives, given its reluctance to make substantial rulings on such issues could result in legal precedents that prove detrimental to applicants in other cases. The RMI v. UK case changed the international legal landscape by introducing a higher threshold for a legal dispute. While this new threshold could potentially trigger a legal dispute, disarmament advocates have to reflect on whether international arbitration is the appropriate method to pursue their objectives. They also should decide whether to reinforce the connection between the TPNW and Article VI of the NPT in future NPT forums. In the long road toward disarmament, it appears that a new fight has just begun. FootnotesMarshall Islands v. United Kingdom, Application, 2014, ICJ, paras. 86-92. http://www.icj-cij.org/files/case-related/160/18296.pdfMarshall Islands v. United Kingdom, Judgement, 2016, ICJ, para. 59. http://www.icj-cij.org/files/case-related/160/160-20161005-JUD-01-00-EN.pdfFor a summary of relevant case law on this subject, see Marshall Islands v. United Kingdom, Judgement, 2016, ICJ, paras. 37-40.Marshall Islands v. United Kingdom, Judgement, 2016, ICJ, para. 41.Marshall Islands v. United Kingdom, Dissenting Opinion of Vice-President Yusuf, ICJ, 2016, para. 8. http://www.icj-cij.org/files/case-related/158/19138.pdfAlleged Violations of Sovereign Rights and Maritime Spaces in the Caribbean Sea (Nicaragua. Colombia), Preliminary Objections, Judgment, ICJ, 2016, para. 73.Marshall Islands v. United Kingdom, Judgement, 2016, ICJ, para. 50. The RMI statement made at the Nayarit Conference was rejected because the United Kingdom was not present.Joint Press Statement from the Permanent Representatives to the United Nations of the United States, United Kingdom, and France Following the Adoption of a Treaty Banning Nuclear Weapons, US State Department, July 7 2017. https://usun.state.gov/remarks/7892Austrian Statement to First Committee, 12 October 2017 http://reachingcriticalwill.org/images/documents/Disarmament-fora/1com/1com17/statements/12Oct_Austria.pdf ; See also Irish Statement to First Committee on 12 October 2017. http://reachingcriticalwill.org/images/documents/Disarmament-fora/1com/1com17/statements/12Oct_Ireland.pdfGeneral and complete disarmament: taking forward multilateral nuclear disarmament negotiations, First Committee Working Paper A/C.1/72/L.6, October 6 2017. http://reachingcriticalwill.org/images/documents/Disarmament-fora/1com/1com17/resolutions/L6.pdfThe Marshall Islands cases were the second time that the ICJ was requested to pronounce on an issue related to disarmament. Previously, it produced an Advisory Opinion in 1996 on the legality of the threat or use of nuclear weapons, in which it acknowledged the unique nature of nuclear weapons, but was unable to reach a conclusion on its legality when used “by a State in an extreme circumstance of self-defence”. Legality of the Threat or Use of Nuclear Weapons, Advisory Opinion, 1. C.J. Reports 1996, p. 226 http://www.icj-cij.org/files/case-related/95/095-19960708-ADV-01-00-EN.pdfFor example, see Malcolm Shaw, International Law, Cambridge University Press, 2017, p. 811.