Introduction

My answer to the question ‘Does the European Union need a Constitution?’ usually reads something like: ‘What about the Treaty on European Union?’ This obviously does not do justice to the legal, political and philosophical insights offered by the debate on European constitutionalism, as it has taken place ever since the launch of the European project in the 1950s. For those active in international institutional law, however, the constituent treaty of an international organisation – a label that still fits the European Union – forms the ‘constitution’ of the organisation, defining the scope and content of the legal order created by it. This definition of a constitution comes close to a classic one presented by Verdross – one of the godfathers of ‘international constitutional law’ – who, in 1926, looked at a constitution in terms of a sustainable institutional basis of a legal community. A constitution of an international organisation thus, primarily, defines an institutional framework whereby competences are being divided among institutions in a way that cannot be changed overnight.