CYIL vol. 9 (2018)

CYIL 9 ȍ2018Ȏ CUSTOMARY INTERNATIONAL LAW, INTERPRETATION OF TREATIES … 11-week session of 2018, the ILC was able to discuss the following topics: “Identification of customary international law”, “Subsequent agreements and subsequent practice in relation to the interpretation of treaties”, “Protection of the atmosphere”, “Provisional application of treaties”, “Jus cogens”, “Protection of the environment in relation to armed conflicts”, “Succession of States in respect of State responsibility”, and “Immunity of State officials from foreign criminal jurisdiction”. The Commission successfully completed its debate and adopted, on second reading, the draft conclusions with commentaries on “Identification of customary international law” and “Subsequent agreements and subsequent practice in relation to the interpretation of treaties”. Two other topics were completed on first reading. Other topics represent the work in progress, some of them are closer to a final product, while the others are still at the early stages of study by the ILC. Therefore, this contribution will provide brief information on all topics on the programme of the Commission. 2.1 Identification of customary international law The Commission had before it the fifth and final report of the Special Rapporteur, Sir Michael Wood, 3 which addressed the comments and observations made by States on the draft commentaries adopted on the first reading. The ILC also had before it an addendum to that report providing an updated bibliography on the topic, 4 the comments and observations received from the Governments 5 and the memorandum by the Secretariat on ways and means for making the evidence of customary international law more readily available. 6 The fifth report did not bring important changes to the draft conclusions as adopted on the first reading. Following the debate in plenary and in the Drafting Committee, the Commission adopted, on the second reading, a set of 16 conclusions together with commentaries. Conclusion 1 provides that the draft conclusions concern the way in which rules of customary international law are to be determined, that is, the legal methodology for undertaking that exercise. 7 Part Two comprises two draft conclusions. Conclusion 2 sets out the basic approach, the two-element approach, according to which “to determine the existence and content of a rule of customary international law, it is necessary to ascertain whether there is a general practice that is accepted as law ( opinio juris )”. 8 Draft conclusion 2 makes clear that the presence of only one constituent element does not suffice for the identification of a rule of customary international law. Conclusion 3 concerns the assessment of evidence for the two constituent elements of customary international law, i.e. a general practice and opinio juris . Paragraph 1 underlines that “regard must be had to the overall context, the nature of the rule and the particular circumstances in which the evidence in question is to be found”. 9 As explained in the commentary, the nature of the rule in question may also be of significance when ascertaining whether there is a general practice that is accepted as law. In particular, “where prohibitive rules are concerned, it may be sometimes

3 See doc. A/CN.4/717 (2018). 4 See doc. A/CN.4/717/Add.1 (2018). 5 See doc. A/CN.4/716 (2018). 6 See doc. A/CN.4/710 (2017). 7 See doc. A/CN.4/L.918/Add.1, p. 3.

8 Ibid., p. 4. 9 Ibid., p. 6.

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