Ireland's Green Party, part of the ruling coalition, votes by a two to one majority to campaign for the Treaty of Lisbon prior to the 2 October referendum.
- France 24
- Ireland approves the European Union's Treaty of Lisbon by a margin of 67.1% to 32.9% in a second referendum.
- Voters in Ireland go to the polls for a second referendum on the Treaty of Lisbon.
- The European Commission denies accusations that it broke Ireland's laws against using taxpayers' money on referendum spending after an EU office in Dublin paid EUR150,000 to insert a guide to the Treaty of Lisbon into all Sunday newspapers as the country's second referendum approaches.
- Czech President Vaclav Klaus says he is "adamant" Irish voters will reject the European Union's Treaty of Lisbon when they vote on it again in the country's 2 October referendum, meaning his unwillingness to sign the treaty will be justified.
- President of the European Commission Jose Manuel Barroso arrives in Ireland on the campaign trail for the country's second referendum on the Treaty of Lisbon.