CYIL vol. 8 (2017)

PAVEL CABAN CYIL 8 ȍ2017Ȏ I. At its sixty-eighth session (2016), the International Law Commission adopted, on first reading, a set of 16 draft conclusions, together with commentaries thereto, on identification of customary international law. 1 Part IV of the draft conclusions [“Accepted as law ( opinio iuris )”] deals with the second constitutent, the “subjective” element of customary international law (in addition to general practice as an “objective”, “material” element). Conclusion 10, included in this Part, describes the forms of evidence of acceptance as law, which, according to the conclusion, “may take a wide range of forms”, including “official publications; government legal opinions; diplomatic correspondence; decisions of national courts; treaty provisions; and conduct in connection with resolutions adopted by an international organization or at an intergovernmental conference. ”2 In addition, draft conclusion 10, paragraph 3 provides that “[f ]ailure to react over time to a practice may serve as evidence of acceptance as law ( opinio juris ), provided that States were in a position to react and the circumstances called for some reaction”. As regards the relevance of such “failure to react” as evidence of opinio iuris , the Commission’s commentary explains that “[t]oleration of a certain practice may indeed serve as evidence of acceptance as law ( opinio juris ) when it represents concurrence in that practice”, but only when two requirements are satisfied in order to ensure that such toleration “does not derive from causes unrelated to the legality of the practice in question”. First, “it is essential that a reaction to the practice in question would have been called for”; according to the Commission, this may be the case, for example, where the practice is one that “(directly or indirectly) affects – usually unfavourably – the interests or rights of the State failing or refusing to act” (and the Commission adds that “[i]t may well be that a certain practice would be seen as affecting all or virtually all States.”). According to the second requirement, “the State concerned must have had knowledge of the practice (which includes circumstances where, because of the publicity given to the practice, it must be assumed that the State had such knowledge), and (…) it must have had sufficient time and ability to act”. 3 The purpose of this article is to comment on whether this brief and general conclusion on the significance of the “failure to react” as one of constituent elements of customary international law appropriately reflects the practice of states in various relevant contexts and whether there could not be any unintended legal ramifications of this general conclusion. II. It seems that in the draft conclusion 10, paragraph 3, the Commision intends to define the meaning of the concept of acquiescence. 4 According to the Encyclopedia of Public * The article was written in the author’s private capacity. 1 The draft conclusions were submitted, through the Secretary-General of the United Nations, to Governments for comments and observations to be submitted by 1 January 2018. The Commission will then proceed to the second reading of the draft conclusions. For the text of the draft conclusions see ILC, Report of its sixty-eighth session (2016), doc. A/71/10, p. 74 et seq . 2 “Conclusion 10 (Forms of evidence of acceptance as law ( opinio juris )): 1. Evidence of acceptance as law ( opinio juris ) may take a wide range of forms. 2. Forms of evidence of acceptance as law ( opinio juris ) include, but are not limited to: public statements made on behalf of States; official publications; government legal opinions; diplomatic correspondence; decisions of national courts; treaty provisions; and conduct in connection with resolutions adopted by an international organization or at an intergovernmental conference. 3. Failure to react over time to a practice may serve as evidence of acceptance as law ( opinio juris ), provided that States were in a position to react and the circumstances called for some reaction.”. 3 ILC, Report on the work of the sixty-eighth session, doc. A/71/10, pp. 100-101, para. 7. 4 In the text of the draft conclusions or in the commentary to the draft conclusion 10, paragraph 3, the word

108