The key events in the process of institutional reform in the EU leading to the Lisbon Treaty.
This Treaty sets out institutional changes to the EU.
These changes are required to ready the EU for enlargement to the East.
More on the Treaty of Nice
May 2004: The biggest single enlargement of the EU
10 new countries join the EU in its single biggest enlargement.
There are now 25 countries in the EU.
Countries joining the EU in 2004 are: Malta, Cyprus, Slovakia, Slovenia, Czech Republic, Estonia, Latvia, Lithuania, Hugary and Poland.
More on enlargement of the EU
The Constitutional Treaty aims to make the enlarged EU more effective and accountable. It aims to replace all existing Treaties with a single 'Constitutional' Structure. This Treaty, however, is not implemented.
More on the Constitutional Treaty.
The French and Dutch electorate reject the Constitutional Treaty in successive referenda.
After the rejection of the Constitutional Treaty by the French and Dutch voters, the EU enters what has been called the 'period of reflection'. This period is intended to allow EU leaders to consider other ways to re-engage Citizens with the future of Europe. The period of reflection ends in January 2007.
The UK governement sets out to Parliament its approach towards any new treaty.
During its presidency of the EU, Germany presents detailed proposals for a new 'Reform Treaty' (later called the Lisbon Treaty after the city in which it was signed). All EU leaders agree that 'the Constitutional concept... is abandoned'. The 'period of reflection' is over and the Lisbon Treaty is signed off by EU leaders.
Romania and Bulgaria join the EU.
After 25 days of debate, the UK Parliament passes the EU (Amendment) Act.
This Act implements the Treaty in UK law.
Ireland holds a referendum on the Lisbon Treaty, and a 54% majority reject the Treaty.
Ireland is the only country to hold a referendum on the Lisbon Treaty. Ireland has had a referendum on every EU Treaty following a supreme court ruling in 1987.
The UK ratifies the Lisbon Treaty
Ireland holds a second referendum on the Treaty on the 2nd October 2009, and on the 3rd October 2009 it is announced that Ireland has, this second time around, voted 'Yes' to the Treaty.
October and November 2009
Poland ratified the Treaty on the 12th October 2009, and on the 3rd November 2009, the Czech constitutional court ruled that the Lisbon Treaty was in line with the Czech constitution. This ruling was swiftly followed by Czech president Vaclav Klaus signing the republic's instrument of ratification of the Lisbon Treaty.