There is no 'one-size-fits-all' definition of the doctrine of necessity under international law. Its meaning and application under a particular treaty regime depend upon the text of the treaty and its underlying object or purpose. In simplified terms, this is the thesis of Diane A Desierto.
To those regularly engaged in the interpretation of domestic legislation, it may be somewhat surprising that this thesis need be argued for. At least in Australia, it is a fundamental rule of interpretation that the words of a statute should not be read in isolation. Regard is to be had to the context in which they are found and the purpose underlying the statute. At the international level, this rule is, of course, reflected in art 31 of the Vienna Convention on the Law of' Treaties (1) ('Vienna Convention'): 'A treaty shall be interpreted in good faith in accordance with the ordinary meaning to be given to the terms of the treaty in their context and in the light of its object and purpose.' However, according to Desierto, there have been attempts to formulate a singular definition of 'necessity' under international law (in particular, art 25 of the International Law Commission's Articles on State Responsibility ('ILCASR')) and to transpose this definition into specialised treaty regimes: both in shaping the interpretation of existing necessity clauses and in supplying a defence of necessity where none is otherwise available.
In ch 1, Desierto introduces her argument and methodology. In chs 2 and 3, she outlines the 'vast ubiquity of necessity usages' (p 350) in political theory and international relations theory, constitutional and criminal legal orders, and municipal and international orders. These chapters climax in the following conclusions: art 25 of ILCASR does not represent a consensus on the doctrine; codification is a futile exercise; and the doctrine should be permitted to take on different shades of meaning depending on the context in which it is found.
Chapter 4 is where Desierto's thesis is fleshed out. She asserts there are five 'issues' law-appliers should consider when applying art 31 of the Vienna Convention to necessity clauses, consideration of which will assist them in navigating the 'ubiquity of necessity usages', and help them arrive at an interpretation 'most consistent with the intention and expressed will of the States Parties to the treaty concerned' (p 350):
1. Field of application: whether the necessity clause applies to the facts in question;
2. Semantic content: how the treaty defines a situation of emergency or necessity; the range of state measures that may be taken in response; and the treaty's intended effect of such measures on the invoking state's treaty obligations. Desierto submits that: law-appliers should carefully scrutinise and reconcile the text of the necessity clause alongside the text of the treaty, the treaty's purpose and context and (in the case of ambiguity) the treaty's travaux preparatoires.
3. Compliance consequences: the effect that a particular interpretation will have on the institutional implementation of the treaty (while an overly generous interpretation of a necessity clause could institutionalise substantive rule-breaking, an overly rigid interpretation could deter states from joining the treaty regime or incentivise parties to leave the regime altogether);
4. Reviewability: whether the interpretation of the clause is so broad as to put a state's invocation of necessity beyond reproach; and:
5. Interpretative sources: the justification for referring to particular interpretative sources, such as 'relevant rules of international law' under Vienna Convention art 31(3)(c).
In ch 5, Desierto applies this framework to the interpretation of necessity clauses in international investment agreements and international trade law. She submits that the distinct functions of necessity clauses in each regime make it impossible to imply a common applicability and semantic content between them. …