The EU operates wide approval procedures that ensure new members are admitted only when they can demonstrate they will be able to play their part fully as members, namely by:
complying with all the EU's standards and rules
having the consent of the EU institutions and EU member states
having the consent of their citizens – as expressed through approval in their national parliament or by referendum.
Membership criteria – Who can join?
The Treaty on the European Union states that any European country may apply for membership if it respects the democratic values of the EU and is committed to promoting them.
The first step is for the country to meet the key criteria for accession. These were mainly defined at the European Council in Copenhagen in 1993 and are hence referred to as 'Copenhagen criteria'. Countries wishing to join need to have:
stable institutions guaranteeing democracy, the rule of law, human rights and respect for and protection of minorities;
a functioning market economy and the capacity to cope with competition and market forces in the EU;
the ability to take on and implement effectively the obligations of membership, including adherence to the aims of political, economic and monetary union.
The EU also needs to be able to integrate new members. In the case of the countries of the Western Balkans additional conditions for membership, were set out in the so-called 'Stabilization and Association process', mostly relating to regional cooperation and good neighborly relations.
What is negotiated?
The conditions and timing of the candidate's adoption, implementation and enforcement of all current EU rules (the "acquis").
These rules are divided into 35 different policy fields (chapters), such as transport, energy, environment, etc., each of which is negotiated separately. Other issues discussed:
financial arrangements – such as how much the new member is likely to pay into and receive from the EU budget (in the form of transfers)
transitional arrangements – sometimes certain rules are phased in gradually, to give the new member or existing members time to adapt.
Oversight by the EU institutions
Throughout the negotiations, the Commission monitors the candidate's progress in applying EU legislation and meeting its other commitments.
This gives the candidate additional guidance as it assumes the responsibilities of membership, as well as an assurance to current members that the candidate is meeting the conditions for joining.
The Commission also keeps the EU Council and European Parliament informed throughout the process, through regular reports, strategy papers, and clarifications on conditions for further progress.