The Principle of Systemic Integration

Abstract

The proliferation of treaties, international organisations and (quasi)-judicial bodies in the last few decades has ignited an interest in the phenomenon of fragmentation of international law and in addressing any potential pitfalls. In this context, the International Law Commission (‘ILC’) established a Study Group to examine the topic of fragmentation or. as it was renamed, diversification of international law. In the report, finalised by its Chairman Martti Koskenniemi in April 2006, one of the conclusions was that one of the ways in which fragmentation could be addressed was through interpretation and, in particular, Article 31(3)(c) of the Vienna Convention on the Law of Treaties (‘VCLT’). According to this provision, in the process of interpretation ‘[t]here shall be taken into account, together with the context: …(c) any relevant rules of international law applicable in the relations between the parties’. This provision, which reflects customary international law is more commonly known as the principle of systemic integration, a term popularised by McLachlan . Other terms used to describe it have been: • ‘principe d’integration’; • ‘systemic interpretation’; • ‘systemic harmonisation’; • ‘systematic interpretation’; • ‘principle of systematic integration’; and • ‘harmonious interpretation’, to name but a few. For the purposes of this entry, the term that will be used is ‘principle of systemic integration’ to refer both to the rule qua VCLT provision and qua customary international law, unless explicitly indicated otherwise. Despite the fact that in recent years there has been a ‘flowering of case law’ referring to the principle of systemic integration as a consequence of the broader discussion on the fragmentation or diversification of international law , this was not always the case. Thirlway, for instance, doubted ‘whether this sub-paragraph will be of any assistance in the task of treaty interpretation’. This may be partially due to the fact that almost every term in Article 31(3)(c) either remains unclear or was at least at one point hotly contested. Weeramantry, rightly criticizing this vagueness of the text of Article 31(3)(c), noted in Gabcikovo-Nagymaros that this provision ‘scarcely covers this aspect with the degree of clarity requisite to so important a matter’. That is not to say, of course, that the existence of the principle of systemic integration was a direct response to the modern-day fears of fragmentation. On the contrary, the principle in one form or another had found its way both in academic writings and debates (Section B) and in judgments long before the VCLT. One of the most well-known examples is the George Pinson case of 1928, where the Tribunal in no uncertain terms held that ‘[e]very international convention must be deemed tacitly to refer to general principles of international law for all the questions which it does not itself resolve in express terms and in a different way’. There is a plethora of similar pre-VCLT cases, where tribunals found that when interpreting a treaty account should be taken of its wider ‘normative environment’. In order to better grasp the debates surrounding the content of the principle of systemic integration and its role not only in the interpretative exercise but, more generally, in the international legal order, the analysis in the following Sections will resemble concentric circles; starting from the history and content of the rule, and moving outward to its connection with other rules and other sources of international law. More specifically the following Sections focus on: i) the drafting history lato sensu of Article 31(3)(c); ii) the main controversies regarding the content of the principle of systemic integration; iii) the links between this principle and other interpretative rules/maxims; iv) the potentiality of a content change of the principle; and finally, v) its relevance for the interpretation of customary international law.