The Work of the ILC on Subsequent Agreements and Subsequent Practice in the Interpretation of Treaties


On 29 October 2013, before the Sixth Committee of the United Nations General Assembly, Min. Plenipotentiary Andrea Tiriticco, Director for Legal Affairs of the Ministry for Foreign Affairs, expressed the position of the Italian Government on the work of the International Law Commission on the topic of “Subsequent agreements and subsequent practice in relation to the interpretation of treaties”. He stated:

My delegation wishes to express its appreciation for the choice adopted by the Commission to the effect of restricting the scope of its study of originally on the topic of “treaties over times” to that of “subsequent agreements and subsequent practice in relation to the interpretation of treaties”. My delegation believes that his decision will enhance a more focused and effective treatment of one of the most critical issues pertaining to the law of treaties, hence, allowing for a smooth implementation of the programme of work outlined in 2012 and 2013 for the topic at issue. I should also like to congratulate Professor Georg Nolte for his first report on the topic.

The Italian delegation also welcomes the first five conclusions adopted by the ILC at its 2013 session which it finds well suited to the general streamlined approach to the matter. Overall, the conclusions adopted so far seem to meet the general aim to elaborate future drafting propositions with may have a sufficiently robust normative content, while preserving at the same time the flexibility inherent in the concept of subsequent practice. This approach appears to be appropriately evidenced by draft-Conclusion 1 on the “General rule and means of treaty interpretation”. The latter, as we see it, correctly reflects the double role that subsequent practice can play as an authentic means of interpretation under the general rule enshrined in article 31, paragraph 3, letters (a) and (b) of the Vienna Convention, on the one hand, and also as a supplementary means of interpretation under the rule of article 32 of the Vienna Convention, on the other. In this vein, paragraph 5 of the conclusion appropriately reminds that the interpretation of a treaty consists of a “single combined operation”, as originally indicated by the ILC in its travaux préparatoires on arts. 31 and 32 of the Vienna Convention, and further endorsed in the 2006 Commission’s Report on the Fragmentation of International Law.

Mr. Chairman,

My delegation also supports Draft-Conclusion 2, insofar as it emphasises the objective character of subsequent agreements and subsequent practice as evidence of the parties’ common understanding as to the meaning of a treaty. In this respect, the qualification there provided of subsequent agreements and subsequent practice as authentic means of interpretation seems to provide an appropriate complement to the contents of article 31, paragraph 3, letters (a) and (b) of the Vienna Convention. As to Draft-Conclusion 3, it appears to appropriately reflect the approach to the matter authoritatively developed in the case law of the International Court of Justice, with special regard to its 2009 Judgment concerning the Dispute Regarding Navigational and Related Rights. The definitions of subsequent agreements and subsequent practice provided for in Draft-Conclusion 4 appear to be fine-tuned and consistent with the overall approach taken by the Commission on the topic in hand.

As to Draft-Conclusion 5, it addresses a delicate issue, namely that concerning the attribution of subsequent practice relevant for the purposes of treaty interpretation, or that of the determination of the scope of the subjects whose conduct is relevant thereto. Having regard to attribution, the ILC commentary rightly explains that the expression “conduct attributable” is borrowed from the language of the draft articles on State responsibility. However, one may wonder whether the principles on attribution under the law of international State responsibility are fully applicable also to the attribution of conduct relevant on the subject under consideration.

Having regard to the determination of the subjects whose conduct may be relevant as subsequent practice, it is not clear from the combination of the draft-text and the commentary before us whether the important issue of the “collective” conduct – or the so-called ‘institutional practice’, i.e., the conduct of collective organs of international organizations and its bearing its interpretation of the constitutive treaties of such organizations – falls within the scope of para. 1, or 2, of the said Draft-Conclusion. The ILC commentary seems to suggest that statements or conduct of actors, such as international organizations, can reflect of initiate relevant subsequent practice of the parties to a treaty, but should not be conflated with such practice. Consequently, such statements or conduct could not amount per se to ‘subsequent practice’ under arts. 31 and 32 of the Vienna Convention, but could only be relevant for the purposes of assessing the subsequent practice of the parties to a treaty. However, one may also consider the conclusions reached by the International Criminal Tribunal on the Former Yugoslavia in the Tadic case whereby the settled practice of the Security Council to consider internal armed conflicts as a threat to the peace manifests the “common understanding of the United Nations membership in general” and reflects the “subsequent practice of the membership of the United Nations at large”. It is the belief of my delegation that this issue deserves further consideration in the future work of the ILC.

Mr. Chairman,

Finally, allow me to draw the attention of the Commission on the possible interconnections between the topic at issue and that on “Formation and evidence of customary international law”. As subsequent practice for the purposes of treaty interpretation may become a relevant factor for identifying or prove the existence of customary rules.

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