EU Enlargement 2007 and 2013: Bulgaria, Romania, and Croatia

The 2007 and 2013 enlargements of the European Union — the accession of Bulgaria and Romania on 1 January 2007 and of Croatia on 1 July 2013 — completed the fifth wave of EU enlargement and brought the total number of Member States to twenty-eight (before Brexit). These enlargements were characterised by more rigorous conditionality, enhanced monitoring mechanisms, and greater public scepticism than the 2004 enlargement. The accession of Bulgaria and Romania was accompanied by the unprecedented Cooperation and Verification Mechanism (CVM) , a post-accession monitoring framework that remained in place for over a decade. Croatia’s accession reflected the application of lessons learned from previous enlargements, with stricter conditionality and a reformed accession process.

Bulgaria and Romania: The 2007 Accession

Bulgaria and Romania applied for EU membership in 1995 and were recognised as candidate countries at the Helsinki European Council of December 1999. Accession negotiations opened in 2000 and were concluded in December 2004. The Accession Treaty was signed on 25 April 2005. The European Commission’s final monitoring reports in 2006 identified significant outstanding concerns in both countries, particularly regarding judicial reform, the fight against corruption, and (for Bulgaria) organised crime. The Commission recommended postponing accession by one year to 2008, but the Council decided to proceed with 2007 accession while imposing the CVM as a safeguard.

Both countries joined with transition periods similar to those applied to the 2004 accession, including restrictions on the free movement of workers, acquisition of agricultural land, and compliance with certain environmental standards. Unlike the 2004 accession, neither country had fully closed all negotiating chapters, with some chapters provisionally closed subject to post-accession verification. This unprecedented situation reflected the political determination to proceed with enlargement despite incomplete reform progress.

The Cooperation and Verification Mechanism

The Cooperation and Verification Mechanism was established by Commission Decisions 2006/928/EC (for Bulgaria) and 2006/929/EC (for Romania) as a post-accession monitoring framework for judicial reform, corruption, and (for Bulgaria) organised crime. The CVM set specific benchmarks and required the Commission to report regularly on progress. The Commission could impose safeguard measures including suspension of the mutual recognition of judicial decisions and limitation of access to EU funds.

The CVM benchmarks for Romania covered: ensuring a more transparent and efficient judicial process; establishing a National Integrity Agency; fighting high-level corruption; and preventing and fighting corruption in local government. Bulgaria’s benchmarks covered: judicial independence and accountability; combating corruption, particularly in local government and high-level positions; and combating organised crime.

The CVM proved controversial. Romanian and Bulgarian governments resented the continued monitoring, arguing that it created a double standard compared to older Member States. The Commission maintained the CVM for over a decade, with regular reports documenting progress and persistent shortcomings. The CVM was finally lifted for Romania in 2023 and for Bulgaria in 2024, after both countries made sufficient progress in judicial reform and corruption prevention. The mechanism’s legacy is mixed: it provided a framework for continued reform pressure but also created a permanent monitoring status that some considered incompatible with full membership.

Croatia: The 2013 Accession

Croatia applied for EU membership in 2003 and was granted candidate status in 2004. Accession negotiations opened in October 2005 and were concluded in June 2011, following the completion of the Treaty of Lisbon’s ratification and the resolution of a bilateral border dispute with Slovenia that had blocked negotiations for nearly a year. The Accesion Treaty was signed on 9 December 2011, and Croatia became the 28th Member State on 1 July 2013 following a positive referendum in which 66 per cent of Croatian voters supported membership.

Croatia’s accession process reflected lessons learned from the 2004 and 2007 enlargements. The Commission applied stricter conditionality throughout the negotiations, requiring Croatia to demonstrate concrete results rather than mere legislative alignment. The negotiation framework included specific benchmarks for opening and closing each chapter, and the Commission could suspend negotiations if progress was insufficient. The process emphasised implementation capacity, judicial reform, and the fight against corruption, reflected in the closure of Chapter 23 (Judiciary and Fundamental Rights) and Chapter 24 (Justice, Freedom, and Security) as the final chapters to be closed.

Accession Process Reforms

The enlargement experiences with Bulgaria, Romania, and Croatia drove significant reforms to the accession process. The revised enlargement methodology adopted by the Commission in 2020 for Western Balkan candidates built on these lessons: stronger emphasis on fundamental reforms (rule of law, public administration, economic governance) with chapters on fundamentals opened first and closed last; greater use of objective benchmarks and conditionality; reversibility of progress (chapters may be reopened if reform momentum stalls); and enhanced involvement of Member States in the negotiation process.

Impact and Legacy

The 2007 and 2013 enlargements extended the EU’s reach into South-Eastern Europe and the Western Balkans. Bulgaria and Romania’s accession integrated two countries with significant agricultural sectors, lower income levels, and more recent experience of communist rule. Croatia’s accession brought a country with strong public support for EU membership and a demonstrated commitment to reform, though the legacy of the 1991–1995 Homeland War and outstanding issues with neighbouring Slovenia continued to affect regional relations. These enlargements reinforced the EU’s role as a stabilising force in a region that had experienced significant conflict in the 1990s, though persistent challenges of corruption, judicial independence, and rule of law in the new Member States continued to test the EU’s capacity to enforce its standards after accession.