Parameters of the enlargement process


According to Article 49 of the Treaty on European Union, any European country can apply for membership of the Union.

Four principles of enlargement

The Treaty of Lisbon
The Treaty of Lisbon© picture-alliance/dpa

As the number of EU member states increases, the challenge of balancing enlargement with the capacity for and momentum of integration also grows. In recent years, the parameters of EU enlargement policy have developed steadily and have become more concrete.

Within the framework of what is known as the “renewed consensus on enlargement”, the EU has since 2006 focused on an enlargement strategy based on four principles. These are:

  • Consolidation: The EU meets its commitments and keeps the pledges it has made to accession candidates.
  • Conditionality: Candidate countries must uphold the fair but rigorous criteria and conditions for accession.
  • Communication: Greater transparency and improved communication are to ensure broad-based societal support for the enlargement process.
  • Ensuring the EU is capable of absorbing new members: The EU must have the capacity to absorb and successfully integrate new member states without compromising its own ability to take action or its further development.

The German Government is committed to these principles and is working to continue the enlargement process. At European level, it advocates a measured and judicious enlargement policy. Germany insists that the accession criteria be upheld in order to link enlargement with the process of internal EU consolidation. The German Government considers the EU’s absorption capacity and the candidate countries’ suitability for accession to be equally essential in decision‑making.

Legal basis

According to Article 49 of the Treaty on European Union, any European country which respects the principles of the European Union can in theory become a member of the Union:

“Any European State which respects the values referred to in Article 2 and is committed to promoting them may apply to become a member of the Union. The European Parliament and national Parliaments shall be notified of this application. The applicant State shall address its application to the Council, which shall act unanimously after consulting the Commission and after receiving the assent of the European Parliament, which shall act by an absolute majority of its component members.

The conditions of admission and the adjustments to the Treaties on which the Union is founded, which such admission entails, shall be the subject of an agreement between the Member States and the applicant State. This agreement shall be submitted for ratification by all the contracting States in accordance with their respective constitutional requirements. The conditions of eligibility agreed upon by the European Council shall be taken into account.”

Article 2:

“The Union is founded on the values of respect for human dignity, freedom, democracy, equality, the rule of law and respect for human rights, including the rights of persons belonging to minorities. These values are common to the Member States in a society in which pluralism, non‑discrimination, tolerance, justice, solidarity and equality between women and men prevail.”


In preparation for the fifth round of enlargement – the largest in the history of the EU (eastward enlargement) – the European Council formulated accession criteria in Copenhagen in 1993. The “Copenhagen Criteria”, which were defined more precisely through the subsequent enlargement process, provide important orientation for candidate countries.

According to these criteria, accession candidates must fulfil the following requirements to become members of the EU:

  • Political criterion: stable institutions to guarantee democracy, the rule of law, human rights and respect for and protection of minorities;
  • Economic criterion: a functioning market economy and the capacity to cope with competitive pressure and market forces within the EU’s internal market;
  • Aquis criterion: the ability to take on all the obligations of membership, i.e. the entire body of EU law and policy known as the acquis communautaire, and adherence to the aims of political, economic and monetary union.

Striking a balance

The European Council in Copenhagen further emphasised that the Union’s capacity to absorb new members, while maintaining the momentum of European integration, is also an important consideration of both the Union and the candidate countries. The EU’s absorption capacity was long regarded as the “forgotten criterion” of Copenhagen. This condition, over which candidate countries themselves have little influence, grows in significance with each new round of enlargement.

In 1995 the European Council clarified in Madrid that fully taking on the acquis in one’s national law was not in itself sufficient for accession. Accession candidates must also adjust their administrative and judiciary structures to ensure the effective implementation of EU legislation.

The European Council in Luxembourg agreed in December 1997 that compliance with the political criterion agreed in Copenhagen was a prerequisite for the opening of any accession negotiations. By contrast, the economic criterion and the ability to fulfil all the obligations of membership (acquis criterion) were to be assessed in a “forward‑looking, dynamic way”.

For the potential accession candidates in the western Balkans, the EU initiated the stabilisation and association process before the start of the actual accession process. The countries must successfully complete this multi‑step pre‑accession process before the opening of accession negotiations. One important step in this process is the conclusion of a Stabilisation and Association Agreement (SAA), which envisages not only economic association but also the country’s assumption of parts of the acquis as well as cooperation in a variety of political areas. Through the stabilisation and association process, potential candidate countries furthermore commit to intense regional cooperation, promotion of good‑neighbourly relations and reconciliation as well as cooperation with the International Criminal Tribunal for the Former Yugoslavia.

Read more on the principles of the enlargement process on the website of the European Commission

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