Legal issues arising in WTO dispute settlement proceedings

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10.6 Burden of proof

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The DSU does not include any express rule concerning the burden of proof in panel proceedings. The concept of the burden of proof generally has two important aspects in any judicial or quasi-judicial system: (i) Who should “lose” the dispute if the facts remain unclear? In whose favour should a panel decide if, based on the available evidence, it cannot establish the facts necessary to determine whether or not the respondent has violated a certain provision of the covered agreements? For example, Article 11.3 of the Agreement on Safeguards prohibits (WTO) Members from encouraging or supporting non-governmental measures equivalent to a voluntary import or export restraint. How should the panel rule, if the available evidence leaves open whether an alleged act of governmental support has taken place or not? (ii) What level of proof suffices for a panel to establish a fact? Above this level, the panel would consider the fact at issue as established and would base its decision, among other things, upon this fact. In turn, below this level, the panel cannot consider the fact as established; if it is a fact that is necessary to satisfy the legal provision, the panel would rule against the party bearing the burden of proof.

The Appellate Body has recognized that the concept of a burden of proof is implicit in the WTO dispute settlement system. The mere assertion of a claim does not amount to proof. In line with the practice of various international tribunals, the Appellate Body has endorsed the rule that the party who asserts a fact, whether the complainant or the respondent, is responsible for providing proof thereof. The burden of proof rests upon the party, whether complaining or defending, who asserts the affirmative of a particular claim or defence.1

This means that the party claiming a violation of a provision of the WTO Agreement (i.e. the complainant) must assert and prove its claim. In turn, the party invoking in defence a provision that is an exception to the allegedly violated obligation (i.e. the respondent) bears the burden of proof that the conditions set out in the exception are met.2 Such exceptions are, for example, Articles XX and XI:2(c)(i) of GATT 1994.

As regards the required level of proof, the Appellate Body has clarified that the party bearing the burden of proof must put forward evidence sufficient to make a prima facie case (a presumption) that what is claimed is true. When that prima facie case is made, the onus shifts to the other party, who will fail unless it submits sufficient evidence to disprove the claim, thus rebutting the presumption.3 Precisely how much and precisely what kind of evidence will be required to establish a presumption that what is claimed is true (i.e. what is required to establish a prima facie case) varies from measure to measure, provision to provision, and case to case.4



1. Appellate Body Report, US —- Wool Shirts and Blouses DSR 1997:I.  back to text

2. Appellate Body Report, US — Wool Shirts and Blouses DSR 1997:I.  back to text

3. This does not impose a requirement on panels to make an explicit ruling on whether the complainant has established a prima facie case of violation before a panel may proceed to examine the respondent’s defence and evidence (see Appellate Body Report, Korea — Dairy, para. 145). The panel’s task is to balance all evidence on record and decide whether the complainant, as party bearing the original burden of proof, has convinced the panel of the validity of its claims (see Panel Report, US — Section 301 Trade Act, para. 7.14).  back to text

4. Appellate Body Report, US — Wool Shirts and Blouses DSR 1997:I.  back to text



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This interactive training module is based on the “Handbook on the WTO Dispute Settlement System” published in 2004. The second edition of this handbook published in 2017 can be found at here.

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