This chapter addresses the question: ‘Which entity or entities within federations possess treaty-making competence?’. This question is analyzed from an international and a domestic law perspective. Some supranational points of particular attention are also addressed.

The first step in eliciting an answer to this question is determining whether the current state of affairs of international law accepts the possibility for component states to enter into treaties in abstracto. And if it does, does it do so unconditionally or not? The same questions arise regarding supranational law, in this case EU law. Non-EU federations, such as the USA, Australia or Canada are typically not confronted with such supranational level, so that the latter can neither set limitations to the way they divide treaty-making competences within the federation. Switzerland is in this regard a noteworthy peculiarity, because even though it is not a member of the EU, it has built up an extensive bilateral treaty network with the EU, with the inevitable cross-pollination of values and legal principles.

The second step is, if that be the case from an international law perspective, to approach the component states’ treaty-making competence from the selected federations’ national perspectives. Do the different federal constitutions provide their component states with treaty-making competence? And if they do, is this limited or not, and to which degree? This assessment will show that the Belgian view on treaty-making competence for component states is specifically outspoken and peculiar, warranting a more detailed analysis of the Belgian example. In line with the terminology used in the Vienna Convention on the Law of Treaties (VCLT), reference is also made to ‘treaty-making capacity’ in this first section. This should be considered interchangeable with the notion of ‘treaty-making competence’.

TREATY-MAKING AND FEDERATIONS FROM AN INTERNATIONAL LAW PERSPECTIVE

It is uncontested that federations are ‘states’ and can therefore make treaties. Article 6 VCLT reads: ‘Every state possesses capacity to conclude treaties’. The question whether component states possess this capacity and if they do, whether they then act as an organ of the federation or of their own accord, has given rise to a much more lively debate in both the VCLT preparatory works and meetings, as well as in legal literature. It is this question that is addressed hereunder.