Opinion ID: 781722
Heading Depth: 6
Heading Rank: 2

Heading: The Use of Authority in Determining Customary International Law

Text: 107 The District Court anchored its finding of universal jurisdiction over Yousef in the relevant provisions of the Restatement (Third). It erred in doing so because such treatises are not primary sources of international law. While a discussion of the sources of authority from which a court may discover the content of customary international law may seem rarefied, we address this subject here at some length because the incorrect use of such sources can easily lead to an incorrect conclusion about the content of customary international law. In the instant case, misplaced reliance on a treatise as a primary source of the customary international law of universal jurisdiction led to the erroneous conclusion that such jurisdiction existed over the acts charged in Count Nineteen. 108 The Restatement (Third), a kind of treatise or commentary, is not a primary source of authority upon which, standing alone, courts may rely for propositions of customary international law. Such works at most provide evidence of the practice of States, and then only insofar as they rest on factual and accurate descriptions of the past practices of states, not on projections of future trends or the advocacy of the better rule. See note 31, post. Moreover, while a treatise never may serve as a primary source of law, reliance on this section of the Restatement (Third) in particular is error because it advocates the expansion of universal jurisdiction beyond the scope presently recognized by the community of States, as reflected in customary international law primary sources. 31 The District Court's reliance on Yunis for the proposition that it could exercise universal jurisdiction over Yousef similarly was misplaced because the holding in Yunis was grounded in the text of the Restatement (Third). 109