The Cases against the Nuclear Weapons States

Marco Roscini
May 12, 2015

On April 24, 2014, the Marshall Islands filed individual applications before the International Court of Justice (ICJ) against the five nuclear weapon states (NWS) parties to the 1968 Treaty on the Non-proliferation of Nuclear Weapons (NPT) (United States, United Kingdom, France, Russian Federation, China) and the NWS not parties to the NPT (Israel, India, Pakistan, North Korea)[1] claiming a violation of Article VI of the treaty, of its customary international law counterpart, and of the obligation to perform their legal obligations in good faith.[2] So far, the ICJ has registered and listed on its website only the cases against the states that have accepted the compulsory jurisdiction of the ICJ through declarations under Article 36(2) of the ICJ Statute (UK, India, Pakistan), but not those against the states which are reliant on forum prorogatum for jurisdiction.[3] While the ICJ already had the opportunity in the past to address nuclear weapons and nuclear tests, this is the first case specifically dealing with an alleged violation of the NPT. It is not a coincidence that it is the Marshall Islands that brought the cases before the Court: the island state was the location of 67 atmospheric nuclear tests conducted by the United States from 1946 to 1958.[4] The timing is also significant: the applications were filed right after the second Conference on the Humanitarian Impact of Nuclear Weapons in Mexico and just before the NPT Preparatory Committee sessions that ushered in the 2015 NPT Review Conference (April 27 to May 22, 2015).

The Marshall Islands’ applications provide the opportunity to discuss the exact content of the obligations contained in Article VI of the NPT and its alleged customary status.

What Does Article VI of the NPT Require the States Parties to Do?

Under Article VI of the NPT, “[e]ach of the Parties to the Treaty undertakes to pursue negotiations in good faith on effective measures relating to cessation of the nuclear arms race at an early date and to nuclear disarmament, and on a treaty on general and complete disarmament under strict and effective international control.”[5] The Marshall Islands’ applications recall with approval the obiter dictum of the ICJ in the last part of its 1996 Advisory Opinion on the Legality of the Threat or Use of Nuclear Weapons, where the Court famously found that Article VI entails not only an obligation to negotiate, but also “an obligation to achieve a precise result — nuclear disarmament in all its aspects — by adopting a particular course of conduct, namely, the pursuit of negotiations on the matter in good faith.”[6] Neither the Court nor the Marshall Islands’ applications, however, clearly explain what the grounds for such interpretation are.

In order to properly interpret the provision in question, one should apply the rules on treaty interpretation contained in Articles 31–33 of the 1969 Vienna Convention on the Law of Treaties (VCLT). Even though the VCLT does not apply to treaties concluded before its entry into force,[7] the rules on interpretation contained therein are generally considered a codification of pre-existing customary international law and are therefore also applicable to the NPT. The ordinary meaning of Article VI of the NPT does not suggest an obligation to bring the negotiations to a successful conclusion, for instance by adopting a treaty on nuclear disarmament, but only “to pursue negotiations” in good faith. This is confirmed by an interpretation that takes account of the context, in particular of the aspirational language of the preambular paragraph declaring the intention of the parties “to achieve at the earliest possible date the cessation of the nuclear arms race and to undertake effective measures in the direction of nuclear disarmament.”[8] Furthermore, an obligation to conclude an agreement needs to be formulated “with sufficient precision” in order to create valid obligations, and goes beyond an “obligation assumed by two or more parties to negotiate in the future with a view to the conclusion of a treaty.”[9] Compare the vague language of Article VI to the far more specific text of Article III(4) of the NPT, which provides, inter alia, for the obligation of the non-nuclear weapon states to negotiate and conclude safeguards agreements, with specified characteristics, with the International Atomic Energy Agency (IAEA). Finally, the travaux préparatoires, used as supplementary means of interpretation, confirm that it was possible to include Article VI in the final text of the treaty exactly because it did not entail a commitment to conclude a treaty on nuclear disarmament.[10]

This does not mean, however, that Article VI does not have any normative value. The ordinary meaning of the verb “to pursue” suggests that this provision goes beyond an obligation to merely enter negotiations. The Lac Lanoux arbitration award confirms that, in spite of the peculiarities of each case, a state will be in breach of an obligation to negotiate an agreement when it is responsible for “an unjustified breaking off of the discussions, abnormal delays, disregard of the agreed procedures, systematic refusals to take into consideration adverse proposals or interests, and, more generally, in cases of violation of the rules of good faith.”[11] These standards are helpful also to assess the conduct of the NWS in relation to Article VI.

Is Article VI Binding on States Not Parties to the NPT?

The Marshall Islands argues that Article VI has become customary law and therefore binding on all states, even NWS not parties to the NPT.[12] It bases its argument on the fact that the NPT has been ratified by 190 states, on certain sentences of the 1996 ICJ Advisory Opinion, on the several General Assembly resolutions condemning weapons of mass destruction, and on the Security Council’s calls for the implementation of Article VI of the NPT.

It could be counter-argued, however, that the fact that a treaty has been almost universally ratified or that the states parties act in conformity with the terms of the treaty is not, on its own, sufficient evidence of its customary status. One has rather to look at the practice and opinio juris of the states not parties to the treaty and their attitude towards the treaty.[13]

Furthermore, from a methodological perspective, one cannot see how such custom could form without also taking into account the practice and opinio juris of the NWS under the NPT. Indeed, the practice of “States whose interests are specially affected” “should weigh heavily (to the extent that, in appropriate circumstances, it may prevent a rule from emerging).”[14] Although the notion is controversial and has been the subject of debate in the works of the International Law Commission on the identification of customary international law,[15] the states whose interests are specially affected for the purposes of custom formation should be in primis those that have the opportunity to engage in the relevant conduct.[16] Unlike the conventions on chemical and bacteriological weapons, the NPT is based on the distinction between states that are entitled to possess nuclear weapons and those that have accepted the illegality of possessing them.

While it is true, then, that Article VI formally addresses all NPT states parties, this provision “specially” affects only the NWS (at least with regard to the part of Article VI that refers to the cessation of the nuclear arms race and to nuclear disarmament). Indeed, it is those states that possess the weapons whose elimination must be negotiated, and it would make little sense for the non-nuclear weapon states to negotiate nuclear disarmament without the participation of the NWS. The fact that Article VI was what the non-nuclear weapon states asked of the NWS, together with the reaffirmation of the inalienable right to the peaceful uses of nuclear energy and the right to receive assistance in the exercise of that right, in return for giving up the right to possess nuclear weapons confirms that this provision was specifically aimed at the NWS.[17]

To be truly “representative,” therefore, participation in the practice must necessarily also include that of the NWS. An empirical study aimed at establishing whether or not Article VI has achieved customary status should determine whether the conduct of the NWS inconsistent with Article VI, reported in detail in the Marshall Islands’ applications, merely constitutes treaty breach on their part or should be counted in keeping the rule in Article VI from becoming customary international law.


It remains to be seen whether the cases brought by the Marshall Islands against the NWS will reach the merits stage. If any of them does, the ICJ will have an opportunity to clarify one of the controversial provisions of non-proliferation law. This Insight has submitted that Article VI of the NPT does exactly what it says on the tin, i.e., it requires parties to pursue good faith negotiations in order to adopt effective measures on the cessation of the arms race and nuclear disarmament as well as a treaty on general and complete disarmament. It does not oblige the parties to successfully conclude such negotiations by achieving an agreement—a result that is beyond the power of any individual state—although the negotiations, to be meaningful, must be conducted with a view of reaching this result. In this context, the 2015 NPT Review Conference will offer an important opportunity for the NWS to show that they are committed to going in the right direction.

About the Author: Dr. Marco Roscini is Professor of International Law at the University of Westminster School of Law in London.

[1] Whether or not North Korea’s withdrawal from the NPT in 2003 had legal effect is still a matter of debate.

[2] The Marshall Islands also filed a complaint on the same grounds against the United States and various U.S. organs before a U.S. Federal District Court, which was dismissed on February 3, 2015 by a U.S. Federal District Court judge on grounds that the Marshall Islands lacked standing to bring the suit. The case was “nonjusticiable because it involve[d] a political question” and the injury claimed could not “be redressed by compelling the specific performance by only one nation to the Treaty.”  Republic of the Marshall Islands v. United States, 2015 U.S. Dist. LEXIS 12785 (N.D. Cal. 2015), available at

[3] The applications against the U.K., India, and Pakistan can be read at The Court has issued orders to fix the time limits for the submissions of the memorials and counter-memorials by the parties.

[4] Under bilateral agreements between the United States and the Marshall Islands, a Nuclear Claims Tribunal was established to assess and award damages to victims of the nuclear tests.  See, (last visited May 5, 2015).

[5] Treaty on the Non-proliferation of Nuclear Weapons, 729 U.N.T.S. 161, entered into force March 5, 1970 [hereinafter NPT].

[6] Legality of the Threat or Use of Nuclear Weapons, Advisory Opinion, 1996 I.C.J. 226, ¶ 99 (July 8).

[7] Vienna Convention on the Law of Treaties, art. 4, May 23, 1969, 1155 U.N.T.S. 331.

[8] NPT, supra note 4 (emphasis added). But see, step six of the thirteen practical steps to implement Art. VI, 2000 Review Conference of the Parties to the Treaty on the Non-Proliferation of Nuclear Weapons, New York, April 24–May 19, 2000, Final Document, 14, NPT/CONF.2000/28 (Parts I and II) (2000) (“An unequivocal undertaking by the nuclear-weapon states to accomplish the total elimination of their nuclear arsenals leading to nuclear disarmament to which all States Parties are committed under Article VI.”), available at .

[9] Lord McNair, The Law of Treaties, 27, 29 (2d ed., 1961) (emphasis in the original).

[10] Daniel H. Joyner, The Legal Meaning and Implications of Article VI of the Non-Proliferation Treaty, in Nuclear Weapons Under International Law 399 (Gro Nystuen, Stuart Casey-Maslen, & Annie Golden Bersagel eds., 2014).

[11] Lac Lanoux Arbitration (Fr. v. Spain), 24 I.L.R. 101, 128 (1957).

[12] Customary international law is created by the convergence of two elements: practice by a sufficiently representative number of states and other subjects of international law (for instance, international organizations) and “evidence of a belief that this practice is rendered obligatory by the existence of a rule of law requiring it” (opinio juris sive necessitatis). North Sea Continental Shelf (Germany v. Denmark/The Netherlands), Judgment, 1969 I.C.J. 3, ¶ 77 (Feb. 20).

[13] Special Rapporteur of the International Law Commission, Second Report on Identification of Customary International Law, 43–44, U.N. Doc. A/CN.4/672 (May 2014) (by Sir Michael Wood).

[14]Id. at 36.

[15] Sixty-Sixth International Law Commission Session, May 5–June 6 & July 7–Aug. 8, 2014, Report of the International Law Commission, 228, ¶ 168, Supplement No. 10 (A/69/10), available at

[16] The mechanical transplantation of concepts derived from the law of state responsibility, like “injured state,” to custom formation should be avoided. It is also incorrect to argue that, because of the global effects of nuclear explosions, the interests of all states are specially affected: indeed, Article VI does not deal with the use of nuclear weapons, but with negotiations related to their possession.

[17] A commentator has suggested that, while the text seems to give more importance to the non-proliferation and peaceful uses of nuclear energy pillars, a constitutional approach to interpretation that takes into account the subsequent practice of the parties and the purposes of the treaty implies that equal weight should be given also to the disarmament pillar. Nigel White, Interpretation of Non-Proliferation Treaties, in Non-Proliferation Law as a Special Regime 113 (Daniel H. Joyner & Marco Roscini eds., 2012).