This article aims to explain the Commission's decisions after formal investigations in the EU state aid regime. It proceeds from the idea that the Commission is confronted with an enforcement dilemma: it must weigh the benefits of promoting undistorted competition on the internal market against the potential costs of losing member state support. This study explores to what extent characteristics of state aid cases and characteristics of member states influence this dilemma and thereby the Commission's decisions. Based on multilevel logistic regression analysis of a newly created dataset consisting of all formal investigations initiated and decided on by the Commission between 2004 and 2018, we find that aid that has been granted unlawfully and aid consisting of tax measures is more likely to result in a negative decision. Member states characterized by a larger administrative capacity are less likely to face negative decisions.

This article aims to explain the variation in duration of preliminary investigations in the state aid notification procedure. While this procedure is guided by objective standards, preliminary investigations result in an overwhelming majority of cases being approved in combination with a large variation in duration. This study explores the explanatory power of political and managerial factors at the member state and state aid case level to account for this variation. Based on multilevel regression analysis of a newly created dataset, results show that both political and managerial factors at the state aid case level affect the duration of preliminary investigations. No evidence was found for member state level factors having an effect.

The enforcement of EU state aid rules is often portrayed as mainly driven by technocratic standards, but there are indications that political factors also play a role. However, their exact impact and relationship with technocratic factors remain unknown. This article studies under which technocratic and political conditions the Commission approves or does not approve state aid to national airlines. Based on a crisp-set Qualitative Comparative Analysis of all 14 cases of alleged state aid to national airlines between 2004 and 2019, the article shows that both the approval and non-approval of aid are predominantly dependent upon the Commission’s technocratic assessment: a low degree of market distortion turns out to be a sufficient condition for the approval of aid, whereas a high degree of market distortion is a necessary condition for the non-approval of aid. However, in some cases, political factors are decisive in determining enforcement outcomes.