EU Treaty Revision, 1951-2015: Changing Rules and Norms and the Case for Reform

While treaties have always been central to the functioning of the European Union (EU), the frequent recourse to treaty revision is a more recent phenomenon. For almost three decades following the signature of the Treaty of Rome in 1957, EU heads of state or government approved only minor amendments to the European Communities’ founding treaties. The period 1985-2007, in contrast, produced six major treaty revisions. This proliferation of new treaties has been accompanied by a new set of legal rules at the member state level governing the process of treaty ratification. This paper presents evidence concerning the changing constitutional rules and norms governing treaty making in the EU-15 member states between 1951 and 2015. It shows that constitutional rules and norms have tightened across a number of EU member states since the 1990s. Qualified or super majorities are now the norm in most member states when it comes to the ratification of EU treaties, several have introduced referendum locks and constitutional reviews concerning the passage of EU treaties is now commonplace in a number of countries. These trends are understood through a two-level legitimacy approach that highlights the tension between untying hands so as to reduce the risks of involuntary defection and imposing new restraints for the sake of procedural legitimacy. Involuntary defection, it argues, might be a price worth paying for restoring trust in the process of EU treaty revision. Lessons are drawn from processes of treaty ratification and constitutional amendment in other constitutional systems.