Beyond the Vienna Rules
Treaties constitute one of the largest effective components of modern international law. Lawyers routinely have to give meaning to their terms. Mostly this is straightforward, but often enough there are interesting difficulties in deciding what the terms mean and how they apply in novel or unexpected situations.
I have found all the posts and comments extremely interesting, and I am grateful to those who have participated in this discussion. I think that the discussion has reinforced my opening remark that too much should not be expected of the Vienna rules. However, the rules do need to be considered as a starting point for treaty interpretation, giving at least an infrastructure.
As provisions in a treaty, the rules are not themselves all easy to interpret. Professor McDougal pointed this out at the 1969 Vienna conference noting the presence there of the ILC Special Rapporteur (Waldock) as “the best testimony, not always mute” of the impossibility of applying the textuality approach, and that reference to Professor Waldock had often been necessary in tribute “not to his skill in flipping the pages of a dictionary or as a logician, but rather to his very special knowledge of all the circumstances attending the framing of our draft Convention.”
I do, however, agree with Isabelle, that practice in the application of the Vienna rules has shown them not to shut the door on much of what McDougal sought. I think it emerges from the discussion what significance attaches to the further skills required once the relevant material has been identified in accordance with the Vienna rules. These are the skills deployed in evaluating the material and shaping interpretative arguments. However, they are skills which cannot readily be listed, still less reduced to further rules. Nevertheless, at the very least, it may prove to be helpful if treaty interpretation is based on a common foundation in the Vienna rules.