Rónán's PhD research explores the relationship between the Court of Justice of the European Union with the EU legislative branch. It takes the regulation of the freedom of services as the field of study, which is examined via the lens of the implementation of the principle of mutual recognition in legislative instruments, to consider the Court’s impact on legislative negotiations from a doctrinal perspective.

Building on his PhD research, Rónán's current research agenda at Maastricht queries what mutual recognition means as a mode of regulatory and administrative governance, and as a legal rule.