Introduction

The written rules governing dispute settlement before international courts and tribunals are largely silent with regard to evidentiary issues. As a consequence, pronouncements by international courts and tribunals have become a primary source for guidance on the principles that govern the treatment of evidence in international dispute settlement proceedings. In the context of WTO dispute settlement, several specific issues relating to evidence are expressly regulated through rules found in the WTO agreements, or in the working procedures of panels. WTO jurisprudence relating to these issues is largely context-specific, and probably therefore of limited relevance for other areas of international dispute settlement. Beyond those specific provisions, however, Article 11 of the DSU simply instructs panels to make ‘an objective assessment of the facts of the case’, and WTO adjudicators have addressed many questions of evidence in light of general international law concepts and principles. WTO dispute settlement proceedings are often fact-intensive, and this has contributed to the development of a substantial body of WTO jurisprudence clarifying general principles of law relating to evidence. This chapter reviews statements by WTO adjudicators of potentially wider applicability relating to: (i) the burden of proof; (ii) forms of evidence; and (iii) the standard of proof.

Burden of proof

It is well established in WTO jurisprudence that the burden of proof rests on the party that asserts the affirmative of a claim or defence, and that the party that asserts a particular fact is responsible for providing proof thereof. WTO panels and the Appellate Body have expressed their understanding that these and other principles governing the burden of proof in WTO dispute settlement proceedings reflect principles of general international law. WTO jurisprudence offers support for the proposition that there are some situations in which the party that carries the burden of proof need not provide evidence to prove a particular factual assertion, including in some instances where this would involve proving a negative, where the other party admits a fact in a dispute settlement proceeding, where a given fact is widely known, or where the relevant documents and information are in the sole possession of the other party.