The European parliament and the requirements of democratic government

This study ties into the debate about the effect of the EU on its member states. Most studies do not include non-EU cases in their investigations. Therefore, it is difficult to establish the (isolated) causal effect or relative importance of the EU. Moreover, studies with an exclusive focus on EU cases tend to be biased towards EU-level explanations, at the expense of domestic or global explanations. The article examines three strategies to demonstrate the causal importance of the EU. It points to the limits of process tracing and counterfactual reasoning and advocates the comparison of EU member states with non-members or, if research is restricted to EU countries, cases where the source of an EU effect is present with cases where the source is absent.