Overview

One of the most well-worn complaints of modern international law, and especially international investment law, is the sense of increasing fragmentation in the face of specific treaty-based regimes.

Fragmentation has given rise to considerable scholarship debating the extent to which the operation of different regimes constitutes a form of lex specialis or, conversely, can be said to reflect deeper organising principles of CIL.

One of the most elegant attempts to locate specific treaty-based regimes within the context of broader principles is the notion that what is called “systemic integration” (SI) is mandated by Article 31(3)(c) of the Vienna Convention on the Law of Treaties (VCLT), which provides that treaties should be interpreted taking into account “any relevant rules of international law applicable in the relations between the parties”. This theory has most famously been developed and applied to international investment law by Professor Campbell McLachlan,1 building on the work of Professor Sands, whose well-known ICLQ articles arose out of and have been reflected in the ILC’s Study Group on fragmentation of international law.

Despite academic work by Professor McLachlan and others, it remains unclear to what extent the SI theory has been, or can realistically be, applied to investment treaty arbitration practice in a meaningful and effective manner.

To empirically test whether the SI theory does meet practice in the international investment regime, this paper examines the cases brought against Argentina over the last decade, especially under the US-Argentina BIT. In these cases, tribunals were presented with two different exculpatory arguments on behalf of the State: first, the so-called non-precluded measures clause included as Article XI of the BIT; and secondly, the CIL defence of necessity, as codified in Article 25 of the ILC Draft Articles on State Responsibility. The question is to what extent SI principles can be regarded as realistically capable of influencing coherent outcomes in similar cases.

I won’t keep you in suspense. In my view, the evidence does not support the notion of SI as being what I will call outcome-determinative.

This may, but will probably not, be regarded as a novel conclusion.

What I then want to do is consider what this might mean for how we think about international law generally. The thrust of my analysis is in opposition to positivist accounts of international law. To my mind what can be drawn from the Argentina necessity cases supports a more realist account of what some, including Gerald Postema, have called “practical reasoning”.2 Part of the object of this paper is, then, to use the necessity case law to illustrate the ways in which practical reasoning is helpful, perhaps more helpful than systemic integration theory, in understanding the jurisprudence of international law.