13
ordinary meaning of the words of the treaty. But those words must be read in the context of the
treaty as a whole because the meaning of words is always dependent on the context in which they
are used. Finally, it also makes sense to interpret the terms of a treaty in light of its purpose
because, obviously, the contracting States are trying to accomplish something by entering into the
treaty and agreeing on its terms.
58. Although Article 31(1) of the Vienna Convention makes sense, it must also be
acknowledged that it is vague and does not provide any clear, meaningful guidance about the
interpretation of treaties. Most importantly, it does not indicate (and it would be impossible for
any interpretive rules to do so in a reasonable manner) how much weight to give to the ordinary
meaning of the words, the context and the purpose of the relevant provisions of the treaty in any
particular case. For example, if there is a conflict between the ordinary meaning of the words and
the purpose of the relevant provision, Article 31 (1) does not indicate how the conflict should be
resolved.
59. Under Article 32 of the Vienna Convention, other elements, referred to as supplementary
means of interpretation, which include the preparatory work of the treaty and the circumstances
of its conclusion, are only to be considered to confirm the meaning established pursuant to Article
31, or to establish the meaning if Article 31 produces an ambiguous, obscure, absurd or
unreasonable result.
60. Although the United Nations and OECD Model Conventions and Commentaries are
important sources for the interpretation of tax treaties, they are clearly not binding. Their legal
status under the provisions of the Vienna Convention is unclear. At first glance, they appear to be
supplementary means of interpretation under Article 32. If so, they might be considered to be of
limited relevance or importance because they can be used only to confirm the meaning otherwise
established by the application of the principles of interpretation in Article 31 or, as mentioned
above, to establish the meaning if the meaning under Article 31 is ambiguous, obscure, absurd or
unreasonable. The United Nations Committee of Experts and the OECD do not intend the Model
Conventions and Commentaries to have such a limited role. The introduction to the United
Nations Model Convention states that, while its provisions and the Commentaries thereto are not
enforceable and should not be considered as formal recommendations, they are “intended to
facilitate the negotiation, interpretation and practical application of bilateral tax treaties based
upon its provisions.”
12
Similarly, the introduction to the OECD Model Convention indicates that
the Commentaries “can ... be of great assistance in the application and interpretation of the
conventions and, in particular, in the settlement of any disputes”.
13
It is difficult, however, to
justify including the United Nations or OECD Model Conventions and Commentaries as part of
12 United Nations, Department of Economic and Social Affairs, United Nations Model Double Taxation
Convention between Developed and Developing Countries, Introduction, para. 12 (New York: United Nations,
2011).
13 Organisation for Economic Co-operation and Development, Model Tax Convention on Income and Capital,
Introduction, para. 29 (Paris: OECD, 2014).