We recall the general principles applicable to burden of proof in WTO dispute settlement, i.e., that a party claiming a violation of a provision of a covered agreement by another Member must assert and prove its claim.36 In US – Wool Shirts and Blouses the Appellate Body stated that:
the party who asserts a fact, whether the claimant or the respondent, is responsible for providing proof thereof. Also, it is a generally-accepted canon of evidence in civil law, common law, and, in fact, in most jurisdictions, that the burden of proof rests upon the party, whether complaining or defending, who asserts the affirmative of a particular claim or defence. If that party adduces evidence sufficient to raise a presumption that what is claimed is true, the burden then shifts to the other party, who will fail unless it adduces sufficient evidence to rebut the presumption. (original footnote omitted).37
Furthermore, in Canada – Dairy (Article 21.5 New Zealand and US II) the Appellate Body stated explicitly that:
as a general matter, the burden of proof rests upon the complaining Member. That Member must make out a prima facie case by presenting sufficient evidence to raise a presumption in favour of its claim. If the complaining Member succeeds, the responding Member may then seek to rebut this presumption. Therefore, under the usual allocation of the burden of proof, a responding Member's measure will be treated as WTO-consistent, until sufficient evidence is presented to prove the contrary.38 Moreover, the Appellate Body has stated that "[i]t is also well to remember that a prima facie case is one which, in the absence of effective refutation by the defending party, requires a panel, as a matter of law, to rule in favour of the complaining party presenting the prima facie case."39 The Appellate Body also has said that "[a] prima facie case must be based on 'evidence and legal argument' put forward by the complaining party in relation to each of the elements of the claim. A complaining party may not simply submit evidence and expect the panel to divine from it a claim of WTO-inconsistency. Nor may a complaining party simply allege facts without relating them to its legal arguments."40
The Appellate Body has also explained that "[i]n the context of the GATT 1994 and the WTO Agreement, precisely how much and precisely what kind of evidence will be required to establish such a presumption will necessarily vary from measure to measure, provision to provision, and case to case."41
In addition, the Appellate Body in EC – Hormones established that"when that prima facie case is made, the burden of proof moves to the defending party, which must in turn counter or refute the claimed inconsistency."42 As the Appellate Body explained in Japan – Apples, the complaining party is not responsible for providing proof of all facts raised in relation to the issue of determining whether a measure is consistent with a given provision of a covered agreement. Although the complaining party bears the burden of proving its case, the responding party must prove the case it seeks to make in response.43
In this dispute, the European Communities, which has claimed that Mexico acted inconsistently with provisions of the SCM Agreement, the Agreement on Agriculture,and the GATT 1994, thus bears the burden of demonstrating that Mexico acted inconsistently with the relevant provisions of those agreements.