When does the EU commission listen to experts? Analysing the effect of external compliance assessments on supranational enforcement in the EU.

How does the European Commission respond to external expert reports about member states' non-compliance? We theorise that expert compliance assessments affect the Commission's monitoring costs and information about governments' probability of compliance. More precisely, the Commission is likely to launch infringements, when information is provided by institutions with extensive expertise that reveals practical non-compliance. However, reports about severe non-conformity indicate that governments will not reform their policies. Therefore, the Commission is expected to initiate infringements if the domestic conditions are favourable for compliance (government and societal EU support and active civil society). Analysing 63 EU directives and 27 countries, we find that enforcement depends on external expertise and practical non-compliance. Moreover, the Commission launches infringements against severe non-conformity when it is supported by civil society. Thus, the Commission utilises expert assessments strategically and it does not necessarily prioritise high levels of non-conformity. [ABSTRACT FROM AUTHOR]