Accession of new Member States to the European Union (EU) is governed by Article 49 of the Treaty on European Union. A state that wishes to apply for membership of the Union must satisfy two conditions:
it must be a European state;
it must respect the common values of the Member States and undertake to promote them. These are human dignity, freedom, democracy, equality, the rule of law and respect for human rights, including the rights of persons belonging to minorities (Article 2 of the Treaty on European Union).
Accession is not automatic, since it depends on the sufficient preparation of the applicant country and on the EU's capacity to integrate the new member. There is also a pre-accession period, during which the candidate country adapts its institutions, standards and infrastructure in order to meet its obligations as a Member State. The accession process involves compliance with the accession criteria previously mentioned, including adoption and implementation of the acquis.
The acquis is the body of common rights and obligations that is binding on all the EU member states (for example the principles and political objectives of the Treaties or the declarations and resolutions adopted by the Union). Candidate countries have to accept the acquis before they can join the EU and make EU law part of their own national legislation.
The conditions and date of accession, and the adjustments to the Treaties on which the Union is founded must be agreed in the form of an accession treaty between the candidate country and the Member States. To end up with the process, this treaty is signed and ratified by all the Member States and the candidate country in accordance with their own constitutional rules. The European Parliament gives its consent.