Customary International Law is Obsolete

by Roger Alford

That’s the provocative conclusion of the latest research by Joel Trachtman. Trachtman’s articles are typically succinct and seductive, so you owe it to yourself to read the short article (and skim the long appendix).

Trachtman examined 300 different CIL rules and found that only 13 (4.33%) have not been either incorporated in treaties or codified. Trachtman argues that the move toward treaties is because CIL cannot respond effectively to the great modern challenges of international society: global environmental protection, international public health, cybersecurity, financial cataclysm, and liberalization of movement of goods, services, and people. Trachtman also argues that CIL is incapable of addressing enduring challenges of regulating war, protecting human rights, and reducing poverty.

According to Trachtman, the reasons for CIL’s obsolescence are manifold. CIL (1) cannot be made in a coordinated manner; (2) cannot be made with sufficient detail; (3) cannot be made with sufficiently heterogeneous reciprocity; (4) cannot be made with specifically-designed organization support; (5) is not subject to national parliamentary control; (6) purports to bind states that did not consent but failed to object to its formation, and (7) provides excessive space for auto-interpretation by states or undisciplined judges.

For Trachtman, the obsolescence of CIL should lead states to stop arguing about CIL and start legislating mutually beneficial transactions. It should also lead NGOs and advocates to stop trying to “bootstrap a desired CIL past a target state” and instead engage with those states in treatymaking. Academics should “focus our analysis on the politically immanent, interdisciplinary, work of developing proposed rules that are administratively workable and effective, and that achieve actual social goals.” He suggests that the international legal system could survive just fine without CIL. So stop worrying about custom and learn to love treaties.

This is powerful stuff. With this piece Trachtman has done a great service to the academic debate on the relevance of CIL. Perhaps unwittingly, he also has done great service to customary international law by offering a comprehensive appendix that lists 300 of the most important CIL rules. If you want students to quickly grasp the scope and contours of CIL, just peruse the appendix.

Applying Trachtman’s thesis to my world of international economic law, I must concur with much of Trachtman’s argument. International trade law, in particular, is all about negotiating, interpretation, and enforcing treaties. We rarely if ever discuss CIL in a trade class. The very nature of an FTA is that it confers rights and obligations exclusively its Members. The defects of CIL are significant enough that trade law is almost exclusively treaty law.

International arbitration is more complicated. Trachtman only identifies two CIL rules for international economic law (Rule 207 and 208), both codified in the investment chapter of NAFTA Chapter 11. But the norm for investment arbitration is to articulate a general standard of protection in bilateral investment treaties (or FTA investment chapters), and then leave it to arbitral tribunals the task of devising detailed obligations from those general standards. Indeed, most BITs require States to afford investors protection consistent with international law, leaving to tribunals the task of discerning precisely what international law requires. BITs are not codifying CIL, but in a sense they instruct tribunals to create it.

Trachtman would not disagree that CIL is still relevant in limited contexts. He specifically recognizes that occasionally CIL is more precise than a codified rule. International humanitarian law and investment arbitration may be such categories. Likewise, Trachtman would concede that CIL is relevant where the treaty is binding on only a few states, as is the case with rules of state succession.

One can easily find selective instances where Trachtman is wrong. But what I doubt critics will be able to do is refute his general thesis that the codification of international rules through treaties has made CIL increasingly obsolete.

15 Responses

  1. far too simplistic!

  2. Dear Roger, thank you for sharing such an interesting article. I have yet to read Professor Trachtman’s article.

    Broadly understanding his point, I believe the correct word is not obsolete though. It is indeed much more preferable to have a treaty where a State puts on paper the obligation it is assuming. However, CIL helps advance international law in the sense that it creates certain obligations for States even when there is no desire within that State to assume such obligations.

    Thus, without CIL, State’s obligations in the international arena would be much more reduced. This is something I do not believe would be positive, since there are many obligations of customary character that it is obvious that States have (and should have).

  3. I would have thought that whether or not a principle was a part of CIL was a matter of fact – whether or not it was customarily observed among a preponderance of actors.

    I that is right the record of CIL is no more than what has been observed by academic writers or lawyers.

  4. CIL is also largely non-transparent, un-democratic, and undermines needed UN reform. It should have never been in the Restatement.

  5. Importantly, there is no known treaty that binds every actor in the international legal process as a party to the treaty. Indeed, not every state is a party to the 1949 Geneva Conventions (one of the widely ratified treaties), the U.N. charter, etc., and there are other actors with formal participatory roles, such as nations, peoples, belligerents.
    However, CIL is universally binding — and so are rights, duties and competencies jus cogens.
    “Undemocratic”? CIL is among the most democratic forms of law because it rests on general patterns of practice and general patterns of opinio juris — the majority!

  6. It is interesting that there is so much focus here on CIL after it is codified, when this is only one element of CIL. In theory, CIL need not exist in codified form at all. CIL can also be created through the negotiation process of a treaty or legislation, or such a treaty could eventually become CIL through influencing subsequent practice over time.

    As comment above mentioned, there is currently no treaty that has been signed by every state. Treaties can still affect non-parties, but ultimately each treaty has a different means of binding, enforcing, overseeing, and implementing its goals. The consequence of this is that just because something is codified, doesn’t mean it’s going to equally involve everyone in the international community, CIL or not. As these new treaties and rules develop, if states feel obligated on the international level to follow the norms established in those treaties, and also begin to adhere to them, wouldn’t that be CIL working alongside Trachtman’s viewpoint and not against it?

  7. I agree with many of the previous comments. While it may be preferable to codify international legal norms, it’s also important that the international community have CIL to rely on when, inevitably, a norm has not been codified and a state defies it. Maybe we do need more treaties. I just don’t think we need to look at the two as opposed to each other. Treaty law and CIL can work together to create a more complete guide to appropriate state behavior.

  8. This topic was addressed four decades ago by Thirlway in his “International customary law and codification: an examination of the continuing role of custom in the present period of codification of international law” (Martinus Nijhoff Publishers, 1972). The sub-title says it all. Importantly, Thirlway makes the point – as does also the ICJ in North Sea Continental Shelf – that custom may also develop and that the very process of “codification” can contribute to such a development, either by (i) triggering the emergence of new law, (ii) supplementing existing law or (iii) departing from it. In that sense, calling customary international law obsolete seems audacious to me.

  9. Like many of the others, I don’t think obsolete is the right term. While treaties are preferable and most CIL is codified, as has been noted above treaties are not binding on everyone. CIL can and often does fill gaps in treaty coverage as well as leading to the emergence of new norms that may eventually be codified into treaties.

  10. Thanks to Roger for his post, and for the comments. I want to concede that CIL is not fully obsolete, for the reasons mentioned in the comments (and in my paper). The point of my paper is that CIL is increasingly inadequate to address the problems that most concern us, not that it has become useless.

  11. Response…I agree that obsolete goes too far especially when considering cyber security. It seems that the realm of international law and cyber security needs to mature before effective treaties will be effective. Currently, the world has an incredibly difficult time even identifying who is breaching secured sites, what they have taken and when it actually occurred. This is not a problem that needs to be driven by states. The market place needs to invest the resources into handling the problem first. Identify the need for international treaties based on the CIL that has been developed by their best practices.

  12. This is an interesting viewpoint, but, like others have commented, I have to disagree that CIL should be considered “obsolete.”

    Yes, treaties have advantages over CIL. But there are also disadvantages.

    For example, treaties are not generally adopted one tiny provision at a time — they combine many different provisions. That may make states reluctant to bind themselves to treaties, even if they agree with the majority of the principles in them. States may also decline to bind themselves to treaties for political or other reasons. That can lead to situations like UNCLOS, where the US is not a party despite acknowledged that most of its provisions are CIL. In some circumstances, CIL can more universally bind states.

    Additionally, the existence of CIL may be considered an integral part of public international law. Despite the common codification of CIL norms, when a dispute arises between states, there may often be no treaty on point between them. The possibility of looking to general principles of international law was added to the ICJ Statute to avoid the possibility of non liquet; without CIL, the possibility of there being no on-point law would be greater. Even if CIL’s force may be depleted, as many of its provisions are codified, it may still play an important role.

  13. Response…This is an interesting stance regarding CIL. The original post probably was trying to make a point that the binding force of CIL is weak, and the codification process made CIL increasingly obsolete. However, the large percentage of codification into treaties does not necessary mean that CIL is no longer useful, or obsolete. Although the article elaborated several reasons for CIL’s obsolescence, many more reasons that CIL is not obsolete are overlooked. All the seven reasons merely exemplify that codification of treaties is effective and necessary in an international stage. However, the article failed to give credits to CIL that those treaties were born out of the customs. The defects of CIL promote the successive establishment of the relating treaties. In my opinion, different bodies of law serve different purposes in different stages of legal development and global awareness. CIL, in a sense, serves as the harbinger of the international community. States that have higher legal or ethical awareness or greater economic interest would be pioneering a certain practice. Additionally, CIL also serves as a standard of practice for those states who are not party of the treaty because of diplomatic, political, or economic reasons. Under such circumstance, the non party state would be obligated to follow CIL.

  14. Makes sense that treaties are the preferred method by states over CIL and that this trend should continue. While of course CIL does have its limited uses, it is more fundamentally fair for states to rely on those treaties in which they consented to, rather than CIL.

  15. Most treaties only have a select number of parties. Even though CIL principles may be codified between those parties, other countries still follow and make decisions based on similar CIL principles that for them are yet to be codified.

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