European Commission President Jose Manuel Barroso on Tuesday welcomed the German Constitutional Court's ruling that the Lisbon Treaty is in conformity with the German constitution.

"I am confident that with this judgement, the court has cleared the way for a swift conclusion of the German ratification of the Treaty of Lisbon," said Barroso in a statement.

Germany's Karlsruhe-based Constitutional Court on Tuesday ruled that the treaty is compatible with German law but demanded changes to domestic legislation to protect national parliamentary powers, delaying the treaty's ratification.

Barroso expressed confidence that the ratification process of the treaty can be completed in all 27 member states of the European Union (EU) by autumn. The Lisbon Treaty is essential for the EU's capacity to act in the present times, he said.

The treaty has been approved in all member states but Ireland. Irish voters rejected the treaty in June 2008 and a second referendum is planned for October 2009. Of the remaining 26 EU member states, only the Czech Republic, Germany and Poland have not completed their ratification process.

Germany and Poland are yet to deposit their ratification documents while the presidential consent to the approval of the treaty in the Czech Republic has not been granted. Czech President Vaclav Klaus, an ultra euroskeptic, has said he would not sign the document until the success of the Irish referendum.

The Lisbon Treaty, signed in December 2007 by all EU heads of state or government, will pave the way for the EU's institutional reforms and streamline its decision-making procedures.