[Laurence Boisson de Chazournes is Professor of international law at the Faculty of Law of the University of Geneva, Switzerland].
In her chapter, Freya Baetens notes that it is necessary to scrutinize "how concepts, principles and rules developed in the context of other sub-fields could (or should) inform the content of investment law." This scrutiny is well-deserved, as the interrelations of other bodies of norms with the corpus of norms related to investment law have gained traction but remains ambiguous.
The notion of cross-fertilization and that of legal regimes informing one another are abundantly referred to. While I share this a-hierarchical vision (with the caveat of the possible application of
jus cogens and
erga omnes obligations) of the relationships among different bodies of law, one should be cautious so as not to transform a land of its own—i.e., international law—into an archipelago of islands more or less connected, which needs artificially created pathways. There is no reason for international investment law, as a field of public international law
à part entière, not to be incorporated in the universe of international law.
In addition to stressing the need for decision-makers to adopt a systemic view of such interrelationships, Freya highlights the key role that rules of interpretation play in promoting a more unitary approach. Much more attention should be paid to the set of rules as codified in Articles 31, 32 and 33 of the Vienna Convention on the Law of Treaties. These rules should be observed as a set of objective rules (to be interpreted in conformity with the rules they provide for) and not as a menu left to the taste and desire of tribunals.
I would like to draw attention to the concept of mutual supportiveness which has emerged as an interpretative tool. Freya's viewpoint evokes it. It constitutes a lens through which international law is increasingly observed. Mutual supportiveness implies that States and arbitrators should refrain, whenever possible, from construing conflicts between international investment obligations and other legal interests. Moreover, there should be mutual adjustments: on each side, there should be an attempt to prevent the eruption of a conflict. This can be done in an
ex ante manner at the time of the negotiation. Freya's chapter provides some examples in this respect. States bear an important responsibility in this context. The prevention of the eruption of a conflict can also be done in an
ex post manner when a dispute is to be settled. This is where the rules of interpretation play a key role. It undoubtedly focuses attention on the powers of tribunals. The wording and content of investment treaties is of crucial importance in an interpretative context.
The principle of mutual supportiveness has most prominently emerged in the relationships between international trade and the environment, but is not limited to this area. For example, the OECD has incorporated mutual supportiveness as a primary principle in its
Green Growth Strategy Report (2011), encouraging Member States to foster compatibility between their investment-related and environmental policy goals.
I then would like to make two observations related to two so-called sub-fields. One of these deals with human rights considerations, while the other one concerns international humanitarian law.
