Ireland was the only member state to hold a referendum on the Treaty on 12 June 2008 in which the Irish people refused to ratify the Treaty of Lisbon (electoral participation 53,1%, votes in favour of the proposal 46,6%, votes against the proposal 53,4%).  In order to deal with the Irish people’s concerns in respect of the impact of the Treaty of Lisbon in the field of taxation, right to life, education and family, as well as the traditional Irish policy of military neutrality, the Heads of State or Government of the 27 Member States of the European Union at the Meeting of the European Council in June 2009 adopted a decision confirming that the Treaty of Lisbon would not affect the above mentioned matters worrying the Irish people. This guarantee allowed the organization of a second referendum in Ireland. The referendum took place on 2 October 2009 and majority of the Irish voters said yes to the Lisbon Treaty (electoral participation 59%, in favour of the proposal 67,1%, against the proposal 32,9%).  Afterwards, on 15 October 2009, the Irish President Mary McAleese ratified the Treaty of Lisbon.

In Germany, the Treaty of Lisbon was reviewed by the Constitutional Court, likewise it was in the Czech Republic. Though the German Federal Constitutional Court ruled that the Treaty of Lisbon is compatible with the German Basic Law (Constitution of the Federal Republic of Germany), it suspended its ratification until the adoption of an amendment of the so called "accompanying law" regulating the control powers of the Bundestag and Bundesrat in relation to the federal government in certain European matters. The Federal Constitutional Court declared that this law did not grant the Bundestag and Bundesrat sufficient powers in a manner compatible with the Basic Law. The amended accompanying law was adopted in September 2009 thus enabling to complete successfully the ratification process in the Federal Republic of Germany. The Federal Republic of Germany deposited its instrument of ratification on 25 October 2009.

The Lisbon Treaty ratification process was completed by depositing instruments of ratification by all EU Member States with the Government of the Italian Republic – the depositary of the Treaty of Lisbon as well as other international treaties that form the so-called primary EU law. It happened in Rome on 13th November 2009 when the Czech Prime Minister Jan Fischer deposited the instrument of ratification of the Czech Republic during his visit. In accordance with its Article 6 (2), the Treaty of Lisbon will enter into force on 1st December 2009.

Date of deposit of the Treaty of Lisbon instruments of ratification: