The process of European enlargement had a peculiar nature. Prior to accession in 2004, EU law was not yet formally binding on EU candidates’ domestic courts, while the obligation of gradual harmonisation with EU law rested upon them. Consequently, the application of EU law in future Member States presented particularly interesting problems and challenges, and required an understanding of the sophisticated concept of EU law’s persuasive force. The only rational choice was to apply Community law, taking into account not only the limited scope of the legislative texts for harmonisation, but also Community law in its full meaning. This included the texts of European directives, which had to be transposed into domestic law, as well as their reasoning and rationale, which would explain why a particular policy was regulated at the European level; ECJ jurisprudence; and, ideally, also the case law of EU Member States. This article argues that this involves a special type of use of comparative law.