Data and Scripts National Parliaments in the EWM 2025

The Treaty of Lisbon (2009) introduced the Early Warning Mechanism (EWM) as a novel instrument for parliamentary control in EU affairs, granting national parliaments the authority to collectively and conditionally bring EU legislation ‘to a halt’. Despite a rise in Euroscepticism, across a number of EU Member States, only a minority of parliaments actually make use of this mechanism. This poses a puzzle given that Eurosceptics are generally seen to be interested in delaying EU legislation or even bringing it to a halt. This limited engagement could undermine democratic legitimacy and creates a collective action problem. Against this backdrop, this contribution probes into the conditions that explain (in)activity in the EWM. This is done by way of using qualitative comparative analysis. We find that several conditions must be combined to influence parliamentary (in)activity. Significant factors include the combination of political motivation with institutional aspects. Weak upper chambers and Euroscepticism promote activity, while their absence frequently leads to inactivity. Parliamentary resources are also critical.