Can Five Treaty Violators and Two Non-Parties Keep a Treaty Rule from Becoming Custom?: A Reply to Roscini

As always, Marco has provided thoughtful analysis and a strong argument in his most recent blog post on whether NPT Article VI has entered into the corpus of customary international law. Following up on my own earlier post on this subject, I would like to provide a brief collegial counterpoint to Marco’s analysis. And I would note in starting that I think the debate in which we are engaged here mirrors the debate that will indeed be had among the parties to the Marshall Islands ICJ cases, assuming they reach the merits phase.

Marco notes in particular the principle of “specially affected” states and their role in the formation of customary law. I think he has expressed that principle perfectly correctly, and I take no issue with its existence and relevance to the formation of a rule of CIL.

I would, however, offer a counterpoint to the proposition that this principle should be applied to the facts of the situation under current consideration in the precise way in which Marco has posited.

The first point I would make is regarding the question of who, in the specific context of NPT Article VI, are the states “specially affected” by this treaty rule? I think it’s important to bear in mind that the rule in Article VI cannot be viewed in isolation, even for purposes of customary law formation. Article VI is an integral part of the NPT’s Grand Bargain structure of quid pro quo obligations. This package deal in its entirety is the reason that the NPT exists at all – without it, many non-nuclear weapon states would never have agreed to join the NPT. Therefore, I think in the specific context of the NPT, there is a strong argument to be made that all NPT parties are equally “specially affected” by the rule in Article VI.

It should be noted that Article VI by its own terms is made applicable to “Each of the Parties to the Treaty,” and not only to the five Nuclear Weapon States. Marco rightly notes that “Specially affected states are those that had the opportunity to engage in the relevant practice.” I agree with that definition, and I think that because of it, the principle of “specially affected” states in CIL formation is best reserved for those areas of international relations in which only some states have the capacity to engage in the relevant conduct – e.g. landlocked states in the context of the law of the sea. But in the context of NPT Article VI, is it correct to say that only the NWS have/had the opportunity or capacity to engage in the relevant practice, which is nuclear disarmament? I would answer that question in the negative.

As I noted in another recent post, there are a number of cases of states who have engaged in nuclear weapons development programs, and who have at some point, for varying reasons, ceased those programs. In a number of those cases, a major motivating factor was that the states in question wanted to join the NPT, and knew that they could not do so unless they ceased their nuclear weapons programs. It was not a lack of capacity or opportunity to construct nuclear weapons that kept many of these states from doing so, but rather a variety of political and circumstantial reasons leading to their decision to stop their active programs. And since they joined the NPT, many of those states have joined in statements signifying their understanding of NPT Article VI as being legally binding.

Further, there are a number of other states who have never, to the best of my knowledge, seriously engaged in nuclear weaponization programs, but who undoubtedly have the capacity to do so if they so chose. And they have chosen not to do so at least in part because of the strictures of the NPT, inclusive of Article VI. So again, simply because only five states within the NPT regime, and four states outside of it, have chosen to possess nuclear weapons and not to disarm themselves of them, does not mean that these are the only states that have had an opportunity or capacity to do so. Rather, in the case of the five NWS, their choice not to disarm merely constitutes treaty breach on their part, and should not be counted to their credit in keeping the rule in Article VI from becoming CIL.

I would offer as a perhaps imperfect but I think persuasive analogy the case of the Chemical Weapons Convention. I may be wrong, but I doubt that many would argue that the CWC rule prohibiting possession of chemical weapons has not entered into the corpus of customary law, at least since the establishment of the CWC in 1997. However, while by far most states parties to the CWC have or are in the process of disarming themselves of their CW stockpiles, there are still states, both CWC parties and non-parties, who possess or are suspected of possessing CW. Would we say that these CW possessing states both inside and outside of the CWC are states “specially affected” by the prohibition of CW because of this possession, and that they therefore should have a disproportionate influence on the creation of a parallel rule of CIL? I don’t think so. I think we would say simply that state practice and opinio juris do not have to be universal for a rule of CIL to develop, and that in this case there is a supermajority of states who do manifest these elements, and that therefore those that do not are nevertheless bound by the rule which has developed thereby. And furthermore that those within the CWC that possess CW in contravention of the treaty’s terms are merely in violation of the treaty.

As I said in my previous post on this topic, in order to truly establish whether NPT Article VI has indeed entered into parallel customary international law, a rigorous empirical study would need to be made of state practice and opinio juris on this matter, which to my knowledge has not yet been made. Only after conducting such a study, looking at the state practice and opinio juris of both NPT parties and non-NPT parties, could any real conclusions be drawn about whether Article VI has persuasively been established as a rule of custom (BTW I titled this post as I did because I’m not sure one can make heads or tails of either Israel’s or North Korea’s opinio juris regarding nuclear disarmament. Israel doesn’t like to talk about the NPT, and North Korea is, well, nuts).

However, I do think that when that study is done, the points I have made about the possible application of the principle of “specially affected” states should be borne in mind. Again, I would argue that in the specific case of NPT Article VI, this principle is not properly applicable as a principle hindering the creation of parallel customary law.