Irish declaration
The European summit in Brussels in June 2009 adopted a declaration concerning Ireland to help the Irish government to have a new referendum for 2 October 2009 on the Lisbon Treaty. The Treaty was originally rejected by the Irish voters in a first referendum on 12 June 2008.
The declaration has the form of a "decision" in the European Council. It is modelled on a similar decision adopting the Edinburgh declaration in December 1992 following the Danish rejection of the Maastricht Treaty on 2 June 1992.
The decision states explicitly that it does not change anything in the Lisbon Treaty. Therefore it did not need to be ratified by the member states. If it had added a new interpretation to just one single article, the full treaty would have had to be ratified again by all the member states.
The decision was sad to be "legally binding" under international law and was archived in the United Nations register of international treaties. It cannot bind the European institutions since only the EU Court has the sole right to interpret the treaties according to Article 344 TFEU.