The Czech Republic's President Vaclav Klaus has signed the European Union's Lisbon Treaty, meaning the process of its ratification is complete.
The treaty - drawn up to streamline decision-making in the 27-member EU - is set to come into effect in December.
Here we chart the treaty's journey and the obstacles it has faced along the way.
Dec 2001: The Laeken Declaration commits the EU to greater democracy and paves the way for a constitution.
The declaration's two main goals are to make the EU more efficient as it expands and takes on new roles, as well as to bring it "closer to the people".
June 2004: The European Constitution is agreed by EU leaders in Brussels, bringing together for the first time the many treaties and agreements on which the EU is based.
The ratification process begins.
May 2005: French voters overwhelmingly reject the constitution in a referendum. Almost 55% of people vote "No", with 45% in favour.
June 2005: Dutch voters also overwhelmingly reject the constitution in a referendum. The final results indicate 61.6% of voters are against the charter and 38.4% approve of it.
Late 2005-early 2007: European Commission President Jose Manuel Barroso admits the EU will not have a constitution for "at least two or three years". The body enters a period of reflection.
The European Constitution is suspended.
March 2007: The Berlin Declaration is adopted, outlining members' intentions to agree on new treaty.
It says the EU should be placed on a "renewed common basis" before the 2009 elections to the European Parliament.
Oct 2007: Leaders reach a deal on new treaty designed to speed up decision making.
It creates a new president of the European Council and a new EU foreign affairs chief but the 250-page document is stripped of any trappings of a super-state, such as the mention of the EU anthem and flag.
Dec 2007: EU leaders sign the treaty in Lisbon. Although the treaty is a replacement for the EU constitution, they insist the two texts are in no way equivalent.
UK Prime Minister Gordon Brown belatedly signs the treaty, having missed a ceremony attended by leaders of the 26 other member states.
Dec 2007: Hungary becomes the first country to ratify the treaty.
June 2008: Voters in the Irish Republic reject the treaty in a vote by 53.4% to 46.6%.
Irish PM Brian Cowen says he respects the vote but admits it has caused a "difficult situation" that has "no quick fix".
Nov 2008: The parliament's ratification of the document is halted pending a decision by the Czech constitutional court on whether the treaty is compatible with the country's constitution. It rules that it is.
Czech President Vaclav Klaus, a Eurosceptic, argues the treaty undermines Czech sovereignty.
June 2009: Germany's constitutional court rules the treaty is compatible with German law - but suspends ratification of it.
The court says extra national legislation is needed to ensure the German parliament participates fully in adopting EU laws.
Sept 2009: Czech senators opposed to the treaty file a new complaint with the constitutional court. Seventeen Eurosceptic senators sign the petition, despite the fact the Czech parliament has approved the treaty.
President Vaclav Klaus says he will not sign the treaty until the court decides.
Oct 2009: Irish voters endorse the treaty in a second referendum - 16 months after their first vote rejecting it.
About 67% voted "Yes", official results show. Irish Prime Minister Brian Cowen hails a "clear and resounding" endorsement.
Nov 2009: The Czech constitutional court rules for a second time that the treaty is compatible with the country's constitution.
President Vaclav Klaus says he will no longer oppose it.
Dec 2009: The treaty is expected to take effect.