Abstract: | The Early Warning System gives national parliaments the right to intervene in European Union policy-making. This article investigates their incentives to submit reasoned opinions. It analyses the reactions of 40 parliamentary chambers to 411 draft legislative acts between 1 January 2010 and 31 December 2013 by ReLogit models. The article argues that, beyond institutional capacity, political motivation explains cross-chamber and inter-temporal variation. Higher levels of party political contestation over EU integration have a positive effect, but greater party dispersion on the left–right dimension negatively affects submissions. Furthermore, salient and urgent draft legislative acts incentivise parliaments to become active in the Early Warning System. Finally, some findings suggest that minority governments and economic recession represent positive conditions for unicameral parliaments and lower chambers to submit reasoned opinions. The findings are discussed with reference to the role of national parliaments in EU democracy. |