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The Curious Case of Customary International Law and the WTO

- Sidharth Kumar



WTO agreements are not to be read in clinical isolation from public international law” – so declared the WTO Appellate Body in it’s very first judgment in 1996, in the US – Gasoline. This was a cause for celebration in the community of public international lawyers, because the GATT Panel preceding the WTO Appellate Body had often acted in a manner which suggested that the GATT regime was insulated from PIL norms, including those of customary international law. This naturally lead to some dismay and doubts over the acceptability and influence of such norms. If large-scale international legal regimes such as the international trade regime (of which the WTO law constitutes the main part) can simply choose to exclude themselves form the general system of public international law, then the entire PIL jurisprudence remains confined to the ‘positive morality’ of Austin, applicable only when convenient.


Though US – Gasoline acknowledged the existence of PIL within closed systems of law such as the WTO, it was hardly the last word on the matter. The contours of this interaction remained unspecified, and with no precedent value, the decision itself remained open to criticism with the early 2000’s witnessing a heated academic debate over this. In his seminal article published in 2001, Professor Joost Pauwelyn argued that since there is no specified hierarchy of sources in international law, the treaties constituting the WTO agreements remain in fluid interaction with other sources such as customary international law.


Much of the debate eventually ended up revolving around Article 3.2 of the Dispute Settlement Understanding which specifically mentions the applicability of “principles of customary international law” in the interpretation of the agreements. Pauwelyn argued that this was merely a cause of ex abundante cautela, or excess caution, and this did not mean that other customary principles did not apply. On the other hand, Joel Trachtman and others that the drafters of WTO law have specifically excluded other principles of customary international law by their decision not to mention them, and that by reading Article 3.2 as being incorporated out of ‘abundant caution’ we are rendering it redundant, and violating basic principles of treaty interpretation including and expressio unius est exclusio alterius (the expression of one thing is the exclusion of the other); and that provisions must be read so that they do not become a nullity.


In 2006, the International Law Commission’s report on the fragmentation of International Law found that the WTO dispute settlement system constituted a self-contained regime, but the broader system of international trade law was not “fully closed to public international law.” To anyone seeking a final determination on the question, this seems maddeningly vague. But the quest for a final determination itself is perhaps flawed. International law is a slow behemoth, and decades may pass before shifts in legal position are acknowledged. Moreover, trade law, and WTO law in particular, has been built upon an edifice of pragmatism, and it’s understanding has also been guided by the same ever since John Jackson laid the foundations of its study. For better or worse, this pragmatism demands that things remain unsettled and capable of shifting as required, and so it has been. It was John Jackson himself who may have opened the can of worms, when he pressed for the exclusion of any specific mention of the Vienna Convention on the Law of Treaties in Article 3.2, as the United States was not a party to it, and thereby led to the inclusion of the reference to “customary principles” of treaty interpretation, which were quickly and openly acknowledged to be Article 31, 32 and 33 of the VCLT.


The WTO Appellate Body has followed this same pragmatic, uncertain, path when applying customary principles. While the VCLT remains applicable without dispute, the various Panels and Appellate Bodies have often referred to various other customary principles as well as the Draft Articles on State Responsibility, in particular the principle of proportionality, without explicitly commenting on their validity. Thus, a member state may often bring in various principles of customary law in support of their argument, and have such arguments accepted, without any definite jurisprudence on the applicability of such principles being spelt out.


In 2014, the EC – Seal case furthered the jurisprudence a bit more in favour of the idea that WTO law exists within a larger framework of customary international law, when it allowed member nations to violate GATT obligations in order to conserve specific wildlife under the exception granted for ‘public morals.’ As one commentator noted, “If we can protect cute animals under Article XX(a), we can certainly protect fundamental norms of PIL which, almost everyone would agree have a much stronger link with public morality.” This 9-year-old judgment potentially opens the door to incorporate a variety of PIL obligations, arising out of whatever source, into the WTO.


Whether EC Seals eventually ends up leading to its logical conclusion, or whether its jurisprudence will be pulled back and modified, remains to be seen. But it has caused a certain excitement amongst those seeking greater coherence between PIL and WTO Law. Ultimately, the larger question at play is not one of WTO specifically, but of the ability of PIL norms to penetrate and influence competing legal regimes in the international arena. While we are far from such fulfilment yet, each little push by PIL into various potentially closed spaces such as WTO law represents a thrust towards the eventual possibility of PIL norms working as a supra-constitution governing important aspects of daily life for everyone in a globalized world.






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