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’. This tool was used very sparingly, however. This poses a puzzle: why do national parliaments not resort to a mechanism that could in fact have a (conditional) impact on the EU legislative process? 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. We identify two key factors that lead to more parliamentary activity: upper chambers that play a comparatively weaker role at the national level and Euroscepticism. Parliamentary resources are also critical.