The article examines how differentiated national implementation of EU policies affects later European integration – whether it leads to renewed unified vertical integration, differentiated integration, the status quo or renationalisation. It examines the case of geographical indications (GIs), an EU labelling system for food and drink based on place of origin and processes of production. Despite features such as diverse national interests and gastronationalism, differentiated implementation has resulted in renewed unified vertical integration. The article identifies three processes: EU legislative requirements encouraging the establishment of producer groups; European Court of Justice decisions which gave priority to quality over cross-border trade; the use of free trade negotiations to alter EU rules. While the integration outcomes are those expected by neo-functionalist analyses, the processes are more institutionally-based. Differences in implementation may aid rather than hinder further integration due to institutional features of EU legislation and decision making.