158 The task of interpreting international instruments is one of identifying the construction the international community would accord them: CRI026 v Republic of Nauru [2018] HCA 19; 92 ALJR 529 at [22]; citing Queensland v Commonwealth [1989] HCA 36; 167 CLR 232 at 240. The applicable principles include Arts 31 and 32 of the Vienna Convention on the Law of Treaties (1969), which codify relevant rules of customary international law: CRI026 at [22]; see also Riley v Commonwealth [1985] HCA 82; 159 CLR 1 at 15 (Deane J). A treaty is to be interpreted in good faith, by giving its terms their ordinary meaning in their context, in light of its object and purpose: Art 31(1). Treaty terms are to be construed in light of the parties' common intention at the time of the treaty's conclusion: Dispute regarding Navigational and Related Rights (Costa Rica v. Nicaragua), Judgment, ICJ Reports 2009, p. 213, 242 at [63]–[64].
159 Under Art 32 of the Vienna Convention, recourse can also be had to supplementary means of interpretation, including the treaty's preparatory works (called travaux préparatoires) to confirm the meaning identified in applying Art 31, or to determine the meaning where application of Art 31 leaves the meaning ambiguous or leads to a manifestly absurd or unreasonable result. Considerable weight must be given to convention committees' interpretative statements: CRI026 at [22], citing the International Court of Justice's statement to the same effect in Ahmadou Sadio Diallo (Republic of Guinea v. Democratic Republic of the Congo) [2010] ICJ Rep 639 at 664 [66]. However, as a cautionary note, it is unclear as to how this approach fits in with Arts 31 and 32 of the Vienna Convention: see, Danae Azaria, "The Legal Significance of Expert Treaty Bodies Pronouncements for the Purpose of Interpretation of Treaties", International Community Law Review 22 (2020) 33–60, see especially discussion of Ahmadou Sadio Diallo at 40–41.
160 As noted above at [70], s 9(10) of the SDA provides that the prescribed provisions, which include s 22, have effect to the extent that they "give effect to a relevant international instrument"; and s 4 defines "relevant international instruments" to include CEDAW and the ICCPR. The combined effect of s 9(4) and (10) is that s 22 will be given effect to the extent that it implements Australia's obligations under relevant international instruments: AB v Registrar of BDM at [96] (Kenny J, Gyles J agreeing).
161 The Commissioner contends that s 22, read with s 5B, is supported by s 51(xxix) of the Constitution, as an enactment of Australia's obligations under CEDAW and, in the alternative, under Art 26 of the ICCPR. Ms Tickle adopts that submission; the respondents dispute it.
