Following the successful ratification of its European Union Accession Treaty by the national parliaments of the 27 Member States, the Republic of Croatia is set to join the EU as the 28th member on July 1 this year. This event will mark an end to the Croatian EU integration journey, which formally started with the opening of the accession negotiations in the 2005. The Accession Treaty arranges accession of Croatia to the EU and European Atomic Energy Community, and amends earlier treaties of the European Union. As such, it is an integral part of the primary law of the EU.

The substance of the negotiations between the European Union and a membership-aspiring country is the acceptance, by the prospective member, of the so-called acquis communautaire. The acquis basically represents the complete accumulated legislation of the European Union, ever since its formation in the early 1950s — also known as EU law. Accession negotiations in other words imply: rights and obligations attached to the European Union system and its institutional framework, the legislative alignment with it by the prospective member state, and finally, the effective implementation of the acquis communautaire by the future member state. By closing the negotiation process with the signing of its EU Accession Treaty in December 2011, Croatia has fully harmonized its domestic legislation with EU law. In practical terms, this means that a large body of rules and regulations governing the political, administrative, social and economic life of the European Union and its Member States shall now be fully extended to the territory of Croatia as well.

It is important to note that the Croatian negotiating process, while sharing the basic principles with the previous five EU enlargement phases, has had several very important novelties in terms of methodology. It introduced the idea of an open-ended process of negotiation, the system of benchmarking, the monitoring of provisional closure of the negotiating chapters, as well as the so-called suspension clause. In this way, it has established a new basic standard for all the future enlargements of the European Union.