Practice makes perfect – the High Court of Australia and Articles 31(3)(a) and (b) of the Vienna Convention on the Law of Treaties – Part 1

This post is the first of a two-part series discussing the High Court of Australia’s approach to the use of subsequent agreement and practice as a means of treaty interpretation pursuant to the Vienna Convention on the Law of Treaties 1969.

Due to the internationalisation of Australian domestic law, Australian courts are increasingly tasked with interpreting treaties that appear in domestic law (which I refer broadly to as ‘incorporated treaties’). The position in Australia appears to be that incorporated treaties are interpreted according to the Vienna Convention on the Law of Treaties 1969 (VCLT). Despite this clear position, there is a lack of clarity from the High Court on the use of subsequent agreement and practice under Articles 31(3)(a) and (b) of the VCLT to interpret incorporated treaties. 

This series suggests the High Court’s hesitance to refer to Articles 31(3)(a) and (b) materials may stem from concerns regarding Australia’s separation of powers.  Whilst these concerns are legitimate, I suggest that the Court should – absent any conflict with Australia’s separation of powers – consider subsequent agreement and practice to interpret incorporated treaties.

The beginning

The first High Court case to consider VCLT Articles 31(3)(a) and (b) materials to interpret an incorporated treaty was Minister for Home Affairs v Zentai (2012) 246 CLR 123 (Zentai). Zentai was alleged to have committed a war crime in Hungary in 1944. Following Hungary’s request for Zentai’s extradition, the Minister agreed that he be surrendered to Hungary. The subsequent dispute centered on the Treaty on Extradition between Australia and the Republic of Hungary (Extradition Treaty). The Extradition Treaty is annexed to the Extradition (Republic of Hungary) Regulations (Cth) which provides that the Extradition Act 1988 (Cth) (Extradition Act) operates subject to the Extradition Treaty. I note that bilateral extradition treaties are not strictly ‘incorporated’ into Australian statute because the Extradition Act applies ‘subject to’ a bilateral extradition treaty.  

Pursuant to Article 2(5)(a) of the Extradition Treaty, extradition may only be granted where ‘the offence in relation to which extradition is sought … was an offence in the Requesting State at the time of the acts or omissions constituting the offence’. This was relevant because Hungary only criminalised the offence of ‘war crimes’ in 1945, one year after Zentai’s alleged conduct.  

The Minister argued that Hungary’s request for Zentai’s extradition, and Australia’s accession to that request, amounted to subsequent practice under Article 31(3)(b) which confirmed that Article 2(5)(a) would not preclude Zentai’s extradition. In the alternative, the Minister argued that the decision to extradite Zentai constituted an Article 31(3)(a) subsequent agreement between Australia and Hungary.  

The Court rejected the Minister’s submissions on two bases. First, the majority (Gummow, Crennan, Kiefel and Bell JJ) held that Article 2(5)(a) of the incorporated treaty was ‘not susceptible of altered meaning reflecting some understanding reached by the Ministry of Justice of Hungary and the Executive branch of the Australian Government’ (at [65]). This was because the Executive required the ‘authority of statute to surrender a person for extradition’ (at [65]). Therefore, the Executive’s power to extradite Zentai could not derive from a subsequent agreement or practice between Australia and Hungary. Secondly, French CJ held that, for the purposes of domestic law, a treaty could only be interpreted by reference to extrinsic materials that existed at the time the treaty was incorporated into statute (at [36]). Therefore, the Minister could not rely on any agreement or practice that post-dated the incorporation of the extradition treaty into statute. 

The great divide 

Shortly after the Court decided Zentai, the High Court was presented with another opportunity to consider extrinsic materials in Maloney v The Queen (2013) 252 CLR 168 (Maloney). In this case, the High Court was divided on whether certain international materials could be used to interpret section 8(1) of the Racial Discrimination Act 1975 (Cth) (RDA) which incorporated the term ‘special measures’ from the International Convention on the Elimination of All Forms of Racial Discrimination (CERD). It is worth noting that the materials in dispute were pronouncements of treaty bodies and not statements of the treaty parties themselves (specifically, the Court considered General Recommendations of the Committee on the Elimination of Racial Discrimination and an Advice of the Expert Mechanism on the Rights of Indigenous Peoples, among others). I note that pronouncements of treaty bodies are not Article 31(3)(a) or (b) materials of themselves, but ‘may give rise to, or refer to, a subsequent agreement or subsequent practice’. 

Their Honours adopted varied positions on the use of these materials.  Hayne and Crennan JJ adopted the most restrictive position. Hayne J held that recourse may only be had to extrinsic materials that ‘existed at the time the RDA was enacted’, although later materials ‘may usefully direct attention to possible’ construction arguments (at [61]). Crennan J similarly held that later materials could not be elevated over the language of the treaty, but may guide State parties as to their reporting obligations (at [134]). 

Conversely, French CJ and Kiefel J adopted a qualified position. French CJ held that whilst Article 31(3) materials could ‘illuminate’ an interpretation (at [23]), they could not ‘authorise a court to alter the meaning of a domestic law implementing a provision of a treaty’ (at [16]). Kiefel J similarly opined that courts may have regard to views expressed in extraneous materials ‘provided that they are well founded and can be accommodated in the process of construing the domestic statute, which is the task at hand’ (at [175]). It is unclear what Kiefel J meant by ‘accommodated’. Perry J suggested in Tech Mahindra Limited v Commissioner of Taxation [2015] FCA 1082  that Kiefel J was contemplating a situation where extrinsic materials may disrupt Australia’s division of powers, as occurred in Zentai (at [61]). 

Bell and Gageler JJ were the most receptive to extrinsic materials. Bell J held, without qualification, that the meaning of ‘special measures’ may be ascertained by reference to VCLT Article 31(3) (at [235]). However, her Honour considered that the specific materials were not materials of that kind (at [235]), a finding consistent with the International Law Commission’s (ILC) codification of subsequent agreements and practice (ILC Draft conclusions on subsequent agreements and subsequent practice in relation to the interpretation of treaties, Conclusion 13). Without referring to the VCLT, Gageler J stated that the RDA was to be ‘constructed to give effect to those obligations’ under CERD to the ‘maximum extent that its terms permit’ (at [326]). His Honour suggested that what is required by those obligations will turn on the ‘content attributed to them by the community of nations’ (at [326]).  

The common thread amongst these judgments is an acceptance that, at the very least, subsequent agreement and practice may ‘illuminate’ an interpretation of an incorporated treaty. French CJ was the only judge to provide a principled reason for this restricted use of VCLT Article 31(3) materials, averring that ‘[o]bligations imposed by international instruments on States do not necessarily take account of the division of functions between their branches of government’ (at [15]). The Chief Justice’s reasoning was clearly influenced by Zentai, which raised identical concerns about VCLT Article 31(3) materials and Australia’s division of powers.

The reprise

A few months after Maloney, the High Court decided Commonwealth Minister for Justice v Adamas (2013) 253 CLR 43 (Adamas). Adamas was tried and sentenced to life imprisonment for corruption in an Indonesian court in absentia. Following Indonesia’s extradition request, the Minister agreed to surrender Adamas. A dispute ensued regarding the interpretation of Article 9(2)(b) of the Extradition Treaty between Australia and the Republic of Indonesia (incorporated through the Extradition (Republic of Indonesia) Regulation 1994 (Cth)) which provides that extradition may be refused where it would be ‘unjust, oppressive or incompatible with humanitarian considerations’.  

The Court issued a unanimous judgment holding that Article 9(2)(b) ‘could not be affected by any subsequent agreement or practice of Australia and the Republic of Indonesia’ (at [31]). Their Honours cited the majority judgment in Zentai in reaching this conclusion and, perhaps cognisant of the inconsistency with the VCLT, made a ‘cf’ (i.e., compare) reference to Articles 31(3)(a) and (b). 

It is interesting that the Court referred to subsequent agreement and practice in their judgment. Neither party had relied on VCLT Article 31(3) materials and the Minister appeared to accept (in a footnote to their written submissions) that a court may not rely on them. On one view, the Court may have been attempting to clarify its position on VCLT Article 31(3) materials following the division in Maloney. However, it is equally possible that the Court was re-affirming the specific rule in Zentai that an incorporated treaty cannot be altered by subsequent agreement or practice where this would conflict with Australia’s division of powers. 

Part two in this series will consider the High Court’s approach to subsequent agreement and practice in Macoun v Commissioner of Taxation (2015) 257 CLR 519 and Addy v Commissioner of Taxation [2021] HCA 34, and will propose how the High Court might approach subsequent agreement and practice in the future.

Samuel Saunders is a Legal Officer at the Attorney-General’s Department Office of International Law. The views expressed in this post do not necessarily represent the views of his past or present employers.