Interactions in a politicised Europe: a scoping literature review and research agenda on the supranational enforcement of EU law by the European Commission

Since the 1990s, extensive research has been done on the supranational enforcement of EU law, for good reason; equal application of EU law in member states is crucial to the legitimacy of the Union, the protection of shared interests, and citizens’ rights. Enforcing EU law, primarily a task of the European Commission as ‘guardian of the treaties’, is rife with intra-institutional, inter-institutional, and inter-level interactions. This article presents a scoping literature review of existing studies on the supranational enforcement of EU law, focussing on the actors involved, the interactions between them, and the theoretical approaches used. We identify which interactions remain understudied and shed light on the theoretical emphases in the literature. Finally, we present a research agenda that can inform research into how preferences and understandings concerning enforcement are shaped and changed through interactions of complex actors within and between institutions, thus expanding the theoretical scope of analyses of EU enforcement.