The European Union (EU) has expanded a number of times throughout its history by way of the accession of new member states to the Union. To join the EU, a state needs to fulfil economic and political conditions called the Copenhagen criteria (named after the Copenhagen summit in June 1993), which require a stable democratic government that respects the rule of law, and its corresponding freedoms and institutions. According to the Maastricht Treaty, each current member state and the European Parliament must agree to any enlargement. The process of enlargement is sometimes referred to as European integration. This term is also used to refer to the intensification of co-operation between EU member states as national governments allow for the gradual harmonisation of national laws.
The EU's predecessor, the European Economic Community,Current Article 1 of the Treaty on European Union reads:"The Union shall be founded on the present Treaty and on the Treaty on the Functioning of the European Union. Those two Treaties shall have the same legal value. The Union shall replace and succeed the European Community". was founded with the Inner Six member states in 1958, when the Treaty of Rome came into force. Since then, the EU's membership has grown to twenty-seven, with the latest member state being Croatia, which joined in July 2013. The most recent territorial enlargement of the EU was the incorporation of Mayotte in 2014. Campione d'Italia joined the EU Customs Union in 2020. The most notable territorial reductions of the EU, and its predecessors, have been the exit of Algeria upon independence in 1962, the exit of Greenland in 1985, and the withdrawal of the United Kingdom in 2020.
Accession negotiations are currently ongoing with Montenegro (since 2012), Serbia (since 2014), Albania (since 2020), North Macedonia (since 2020), Moldova (since 2024), and Ukraine (since 2024). Negotiations with Turkey were opened in October 2005, but have been effectively frozen by the EU since December 2016, due to backsliding in the areas of democracy, rule of law, and fundamental rights.
Bosnia and Herzegovina and Georgia were granted official candidate status respectively in December 2022 and December 2023, but were asked to complete additional reforms before qualifying for the formal start of membership negotiations. Kosovo submitted an application for membership in December 2022. For Kosovo to be granted official candidate status, the Council will need to unanimously agree to start Kosovo's accession process by requesting an opinion from the European Commission on its application. The EU however remains divided on its policy towards Kosovo, with five EU member states not recognising its independence.
Criteria
According to the EU treaties, membership of the European Union is open to "any European State which respects the values referred to in Article 2 and is committed to promoting them" (TEU Article 49). Those Article 2 values are "respect for human dignity, freedom, democracy, equality, the rule of law and respect for human rights, including the rights of persons belonging to minorities." This is based on the 1993 "Copenhagen criteria" agreed as it became clear many former Eastern Bloc countries would apply to join:
In December 1995, the Madrid European Council revised the membership criteria to include conditions for member country integration through the appropriate adjustment of its administrative structures: since it is important that European Community legislation be reflected in national legislation, it is critical that the revised national legislation be implemented effectively through appropriate administrative and judicial structures.
Finally, and technically outside the Copenhagen criteria, comes the further requirement that all prospective members must enact legislation to bring their laws into line with the body of European law built up over the history of the Union, known as the acquis communautaire.
Process
Today the accession process follows a series of formal steps, from a pre-accession agreement to the ratification of the final accession treaty. These steps are primarily presided over by the European Commission (Enlargement Commissioner and DG Enlargement), but the actual negotiations are technically conducted between the Union's Member States and the candidate country.
Before a country applies for membership it typically signs an association agreement to help prepare the country for candidacy and eventual membership. Most countries do not meet the criteria to even begin negotiations before they apply, so they need many years to prepare for the process. An association agreement helps prepare for this first step.
In the case of the Western Balkans, a special process, the Stabilisation and Association Process exists to deal with the special circumstances there.
When a country formally applies for membership, the Council asks the commission to prepare an opinion on the country's readiness to begin negotiations. The council can then either accept or reject the commission's opinion (The council has only once rejected the commission's opinion when the latter advised against opening negotiations with Greece).Article : A success for Konstantinos Karamanli on CVCE.eu
If the Council agrees to open negotiations the screening process then begins. The commission and candidate country examine its laws and those of the EU and determine what differences exist. The Council then recommends opening negotiations on "chapters" of law that it feels there is sufficient common ground to have constructive negotiations. Negotiations are typically a matter of the candidate country convincing the EU that its laws and administrative capacity are sufficient to execute European law, which can be implemented as seen fit by the member states. Often this will involve time-lines before the Acquis Communautaire (European regulations, directives and standards) has to be fully implemented.
A chapter is said to be closed when both sides have agreed it has been implemented sufficiently, however it can still be re-opened if the Commission feels that the candidate has fallen out of compliance.
To assess progress achieved by countries in preparing for accession to the European Union, the European Commission submits regular reports (yearly) to the European Council. These serve as a basis for the council to make decisions on negotiations or their extension to other candidates.
Once the negotiations are complete, a Treaty of Accession will be signed, which must then be ratified by all of the member states of the Union, as well as the institutions of the Union, and the candidate country. Once this has been completed it will join the Union on the date specified in the treaty.
The entire process, from application for membership to membership has typically taken about a decade, although some countries, notably Sweden, Finland, and Austria have been faster, taking only a few years. The process from application for association agreement through accession has taken far longer, as much as several decades (Turkey, for example, first applied for association in the 1950s and has yet to conclude accession negotiations).
On 18 October 2019, France vetoed starting of negotiations with Albania and North Macedonia, citing problems with the current enlargement process. In November 2019, France proposed a seven-stage accession plan for membership. The reformed accession strategy proposes participation in different programs, such as Erasmus, Banking Union, Capital Markets Union, Customs Union, etc.
Example The following is an example of the accession process—Estonia's path to membership from its restoration of independence from the Soviet Union in November 1991 with recognition from the EU the same month to membership in May 2004. Ease of accession depends on the state: how integrated it is with the EU beforehand, the state of its economy and public institutions, any outstanding political issues with the EU and (historically) how much law to date the EU has built up that the acceding state must adopt. This outline also includes integration steps taken by the accession country after it attains membership.
+ Estonia EU membership timeline Year Date Event Notes 1991 20 August Restoration of independence from USSR Recognition from EU in same month. 1994 18 July Free trade agreement concluded 1995 1 January Free trade agreement in force 12 June Europe Agreement concluded 24 November Applied for Membership 1998 1 January Europe Agreement comes into force Aiding pre-integration March Membership negotiations open 6 chapters openedTimetable for accession negotiations by chapter and by country (1998–2004) CVCE.eu 1999 17 chapters opened 2000 6 chapters opened 2002 December All chapters closed and negotiations concluded Final chapter (No. 30) was opened and closed at the same time. 2003 8 April Draft accession treaty approved by Estonian government 16 April Treaty of Accession signed 14 September Referendum on membership approved 66.84% in favour, turnout : 64.02% 2004 1 May Acceded to EU 28 June Joined ERM Requires 2 years in ERM before euro adoption 2007 21 December Entered the Schengen area 2011 1 January Adoption of the euro 1 May Right to limit migration from 2004 countries expired Only Austria and Germany applied this, the rest of EU countries abolished restrictions before 2011
Success and fatigue Enlargement has been one of the EU's successful foreign policies,Piket, Vincent EU Enlargement and Neighbourhood Policy , Institute for Strategic Studies yet has equally suffered from considerable opposition from the start. French President Charles de Gaulle opposed British membership. A later French President, François Mitterrand, opposed Greek, Spanish and Portuguese membership, fearing that the former dictatorships were not ready and that the countries' inclusion would reduce the union to a free-trade area.Beyond Enlargement Fatigue? The Dutch debate on Turkish accession, European Security Initiative 2006
The reasons for the first member states to apply, and for them to be accepted, were primarily economic while the second enlargement was more political. The southern Mediterranean countries had just emerged from dictatorships and wanted to secure their democratic systems through the EEC, while the EEC wanted to ensure the same thing and that their southern neighbours were stable and aligned to NATO. These two principal forces, economic gain and political security, have been behind enlargements since. After the large enlargements in 2004, public opinion in Europe turned against further expansion.
It has also been acknowledged that enlargement has its limits; the EU cannot expand endlessly. Former Commission President Romano Prodi favoured granting "everything but institutions" to the EU's neighbour states, allowing them to co-operate deeply while not adding strain on the EU's institutional framework. This has in particular been pushed by France and Germany as a privileged partnership for Turkey, membership for which has faced considerable opposition on cultural and logistical grounds.Kardas, Saban (13 May 2009) Merkel and Sarkozy Call for Privileged Partnership Angers Turkey, Jamestown FoundationSchauble, Wolfgang (2004) Talking Turkey, Foreign Affairs
Historical enlargements