The Death of a Customary Rule of International Law

by Roger Alford

Like Duncan, I had my first week of public international law. In a brief introductory discussion on customary international law one of the students asked, “How does a practice that has achieved the status of customary international law cease to become customary international law?” It is an interesting question. We spend plenty of time in international law classes discussing the formation of customary international law, but rarely do we examine the death of a custom.

Obviously there are a number of possible answers. A custom may be superseded by a treaty. Likewise, subsequent state practice may conflict with a previous norm, such that the emergence of one norm results in the eclipse of another. But the question also raises the possibility that customary international law may cease to exist under the doctrine of desuetude. It seems quite possible that some customs can become obsolete, but I struggle to think of many examples.

A quick search reveals that the question of applying the doctrine of desuetude to customary international law has rarely been examined by international law scholars. In this article, Michael Glennon has written a little about the doctrine, including the following provocative statement:

The idea of a tipping point, for example, is hardly unique to the notion of desuetude. It is a core problem in the methodology of customary international law formation, which requires the same inquiry in determining the point at which a nascent or emerging customary norm becomes binding. Traditional international law doctrine provides little useful guidance in telling us when that has happened. The emergence of desuetude with respect to a dying norm is no different. At some point, the balance tips; at some point, the rule changes; at some point, obligation shifts. Whether the issue is a rule’s birth or death, the process is the same.

I query whether that is accurate. Customary rules die in the same way they are formed, by reaching a certain tipping point in which they are no longer binding? That would seem to suggest that customary international law can only die when a practice no longer remains general and consistent. On this logic, a rule ignored by the majority of states ceases to be a rule altogether. Or does it remain binding for those minority states that continue with the practice? Is it also possible that a practice remains general and consistent, but that it ceases to be binding because opinio juris falls away? “We used to do it because we felt we had to, but now we don’t think we have to do it, we just do it because we want to do it.” Is that enough?

Just to give you a concrete example, I was at a conference at Stanford a few years ago with a bunch of international tribunal judges. Very impressive crowd. In the context of discussing pacta sunt servanda I made the passing comment that in the WTO context it appears patently clear that almost every prominent state is engaging in “efficient breach” behavior, making certain policy choices not to comply with WTO panel decisions and pay the consequences (including monetary penalties in the form of sanctioned tariff increases). Not surprisingly, I received a vigorous challenge from one of the most eminent judges in the world (who, by the way, was not a WTO expert). But the judge never answered the question as applied to the specific context in which I raised it. Is it possible that the doctrine of pacta sunt servanda (which of course is both a VCLT treaty obligation and a customary norm) is no longer followed at least in certain contexts? And if so, what does that say about the norm?


16 Responses

  1. Interesting question, indeed.
    Stipulating that rules may ‘die’ as a result of widespread flagrant breaches obviously doesn’t make much sense. Some rules of international law are often honored in breach.

    Another interesting question is what happens when a treaty becomes customary (for instance, the Hague Regulations) and states want to ‘kill’ a certain provision. Can the provision lose its customary status and retain its conventional status, in a way that binds only state parties? Or should state parties give up the conventional status (using a reservation) in order to kill the customary status?

  2. I think Michael Glennon is highly persuasive on the existence of the doctrine of desuetude, and particularly persuasive in his writings arguing that the Security Council’s role in the use-of-force as stipulated by the Charter’s literal language is in desuetude.  I would have thought that desuetude is an unraveling of the customary law process, in reverse.  State practice falls away – and states do not have a commitment to the rule qua law.  But it’s a very interesting question as to whether there is a special category for the minority that continues to affirm the rule – maybe a parallel category to persistent objectors, persistent affirmers, perhaps?


    There’s an argument in the Digest (i.e. Roman law) that says exactly that: Since the Roman people can come together to make a law, they can also make a law implicitly, through custom. Since the Roman people can come together to abolish a law, they can also abolish it by collectively ignoring it.

    In the case of International Law, the rule that states are only bound by rules they consent to implies that they should be able, on some reasonable terms, to withdraw from both treaties and ICL rules. Presumably, a sufficiently flagrant and consistent breach should do the trick…

  4. I found the cite:

    Digest 1, 3, 32:

    Iulianus libro 84 digestorum
    pr. De quibus causis scriptis legibus non utimur, id custodiri oportet, quod moribus et consuetudine inductum est: et si qua in re hoc deficeret, tunc quod proximum et consequens ei est: si nec id quidem appareat, tunc ius, quo urbs Roma utitur, servari oportet.
    1. Inveterata consuetudo pro lege non immerito custoditur, et hoc est ius quod dicitur moribus constitutum. Nam cum ipsae leges nulla alia ex causa nos teneant, quam quod iudicio populi receptae sunt, merito et ea, quae sine ullo scripto populus probavit, tenebunt omnes: nam quid interest suffragio populus voluntatem suam declaret an rebus ipsis et factis? Quare rectissime etiam illud receptum est, ut leges non solum suffragio legis latoris, sed etiam tacito consensu omnium per desuetudinem abrogentur.

    Or in English:
    Julianus, Digest, Book XCIV



    I would argue it’s the second proposition which makes no sense, not the first.  CIL where every party involved in the conduct refuses to obey (and never entered into a treaty to do so in the first place, yes, Ottawa Treaty, I mean you) is damaging to the entire concept of international law.  What’s the point of a law every interested party ignores?

  6. What’s the point of a law every interested party ignores?

    Just because the law is often or always breached, it doesn’t mean that it is wrong. For example, a society can decide that government officials shouldn’t be bribed. But even if every official is bribed, the act is (and should be) unlawful.

    Similarly, certain rules of occupation law are often, if not always, breached. The international community as a whole can think these rules are necessary and well-founded, even if nearly all states who are occupying powers do not abide by them.
    For a discussion of this honoring-by-breach, see Benvenisti, The International Law of Occupations (2004).

  7. And of course, state behvaior is not the only factor in international law. We must not forget the name of this blog – opinio juris.
    When states breach customary rules, the breach will often be renounced by other states, which will in turn reaffirm the customary status of the rule.

  8. Historically, it seems to me many customary rules were terminated by the gradual proliferation of treaties banning a practice once approved of and regulated by customary rules.  Privateering comes to mind as a possible example.

    Another example of customary norms that slowly became obsolete are those regarding the confiscation of the debts and property of enemy nationals during a general state of war between states.  I suppose we can argue whether this was the end of customary norms surrounding the practice or the development of a limitation on an otherwise unlimited practice.  Regarding this development, the majority and dissenting opinions  in Brown v. US are instructive (though Brown is often cited for a different proposition).

  9. In what way does the ‘efficient breach’ behaviour change the substance of the WTO law rules which are violated? If many decide to drive at 95 miles an hour on the highway every day, and they cannot be bothered to follow the speed limit because they are happy to pay the corresponding fine, surely they are not contributing to the eventual desuetude of the highway code in doing so? In fact, by paying the fine they are affirming the rule – except that the rule perhaps is unfair because it does not provide a sufficient disincentive for everyone involved. The logical result is that a political action is required for the strengthening of the rule through tougher sanctions, not its abolishing.

  10. I think it is important to be careful about analogies between international law and domestic law. Unlike citizens of countries, states can pick and choose which rules they want to recognise. In domestic law, the logic of desuetude, as explained in the article from the Digest that I quoted above, is hampered somewhat by the use of representative government. (Which is what Irnerius wrote in his gnossa to this article.) But in a direct democracy, yes, if everyone ignores the speed limit it should thereby be considered repealed, or at least transformed into a strange form of tax.

    It is essential for the legitimacy of international law that states can withdraw from both treaties and CIL with a reasonable amount of hassle. That is the only way we can sell IL to our republican American friends.

  11. Touché Martin.  Oddly, the “conservatives” are very fond of “undemocratic” customary international law when it suits their purposes.  In witness thereof – the Military Commissions Act’s claiming its crimes are not new, thereby attempting to avoid nullum crimen sine lege (in the U.S., the prohibition of ex post facto laws).  (I do think there is a legitimate, municipal U.S. common law encompassing “law of war” violations that is preserved/recognized in U.S. military law – but it does depend upon applicable international law for its substance.)

    Thanks also for the wonderful quote above.  Do you not think that it tends to undermine your (in my view correct) view that states must consent to a rule and retain the capacity to withdraw their consent?  My limited knowledge of Roman law, which appears to be supported by the quote above,  is that it was imposed on many who were not part of its making (and if even this does not exist, then the law which is used by the City of Rome must be followed).  I assume the laws of the City of Rome were only consented to by its citizens/residents.

    That issue, whether and when a customary norm becomes universally binding,  is still ‘the rub’ today and at the core of Roger’s questions and Glennon’s quote.  Glennon seems to be talking about the point at which customary norms of universal character lose that character.  If this is even possible, the loss of that universal status should not diminish the effect of these norms between those that continue to observe them.

    However, the notion that any customary norm can become universally binding without universal observance is in tension with the classic law of nations formulation offered by Vattel (reportedly widely read by those who drafted the U.S. Constitution).  According to Vattel, customary norms are only binding on those who observe (as he says, tacitly consent to) them.  This is where knowledgeable U.S. conservatives may best base their arguments against universal customary norms.

    This leads one to other questions that Roger raises and I force my students to consider.  How do jus cogens norms develop?  After the positivist transformation of international law, what is the basis for such norms, universal custom or universal general principles of law in nations with developed legal systems?   Do they ever change or lose their obligatory character?  Vattel theorized a “necessary” law of nations – immutable norms binding on all nations (through presumed consent).  These norms were clearly based in Judeo-Christian-laden natural law concepts.  Indeed, Vattel characterized the law of nations as the law of nature applied to nations.  Is pacta sunt servanda a universal customary norm, or an immutable general principle of law?  If the former, Roger’s question regarding state practice is relevant to its existence.  If a general principle, practice is irrelevant so long as it remains a prominent feature of developed legal systems.

    This observation will seem strange to those that consider the norms listed in the ICJ statute as a hierarchy (treaty, then custom, then general principles).  However, it seems to me that a universal general principle of law is the closest analog to Vattel’s “necessary” law of nations – the concept most closely akin to jus cogens and universal customary norms.

  12. @John C. Dehn: Like you said, my understanding of CIL was always that customs are not universally binding unless the two ingredients are universally present. In that sense, it is different from a domestic legal rule in a direct democracy such as ancient Rome, where a majority vote could enact a rule for all, and in a representative democracy, where citizens transfer the power to make laws to a representative body. Like I said before: careful with the analogies.

    I was, like you apparently, somewhat surprised by Alford using <i>pacta sunt servanda</i> as an example. In the context of international law, I wouldn’t consider that a rule of law. Rather, it is simply a different way of saying that international law is law, the same way that the argument that international law is not law always starts by saying that states ultimately decide for themselves which rules to follow at any given time.
    The reason why I keep mentioning “a reasonable amount of hassle” is that there has to be a difference between a state violating a rule of international law and a state revoking its consent to be bound by that rule. Withdrawing from a custom should, at the very least, require a clear, explicit, unequivocal statement saying that the state no longer considers itself bound by a certain rule.
    This does create a problem for <i>ius cogens</i>. Presumably, the only way to fix that is to say that <i>ius cogens</i> is governed by a direct democracy model instead of the normal case-by-case consent model. I have no problem with the hypothetical possibility that a majority of states should de-cogens a rule of law…

  13. Martin,

    I believe we do see the problem similarly.  The issue then becomes at what point should we observe a jus cogens norm.  Is the tipping point analysis an apt one?  Further, if it is apt for jus cogens norms, then why not for customary norms.  If we are to throw consent to the wind, at least in part, it makes little sense to require universal consent for a “mutable” customary norm and only the consent of a majority (or super-majority, or whatever is adopted short of universal) of states for an immutable norm.  How would you justify the different treatment?

  14. Regardless of the Opinio Juris changing, or state practice changing on a wide scale…Shouldn’t the real question be whether it is even possible for something that has been previously recognized as customary international law to simply no longer exist as law?  Wouldn’t that position mean that each time a Customary Internatinal Law is challenged in court that the court must totally re-analyze the conduct of states and the opinio juris instead of just being able to cite precedent?  Wouldn’t that be hugely time consuming for courts?

    I kind of think the only way it could no longer be a Customary International Law, is through being superceded by a treaty provision.

  15. @Michael J. Davis: The court would only have to analyse its own government’s conduct and <i>opinio juris</i>. (Unless, of course, the question is about which law might bind another state.) The existence of precedent, especially supreme court precedent, to the effect that a certain rule is CIL is, of course, itself evidence of <i>opinio juris</i>.

    @John C. Dehn: Maybe we should recognise <i>ius cogens</i> for what it is. CIL itself is already much less important than one would think from reading an international law text, and <i>ius cogens</i> is again an unimportant subset of CIL. The only time it matters is when we need to explain why something like the Nuremberg tribunal doesn’t violate the <i>nulla poena sine lege</i> rule.* So maybe we should simply make do with the rule that if you have to ask whether something is <i>ius cogens</i>, it’s not.

    * For example, look at all the paragraphs used by the Court of First Instance and the European Court of Justice in the Kadi litigation discussing whether the plaintiff’s <i>ius cogens</i> rights had been violated.

  16. … the end of my comment disappeared…

    Clearly the rights that were in play were nowhere near the level of <i>ius cogens</i>, and yet the Courts felt compelled to discuss the possibility in significant detail.

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