WARSAW, October 27 (RIA Novosti) - The Czech Constitutional Court on Tuesday ruled it would return to making a decision in early November on ratifying the Lisbon Treaty.

The court said it was investigating the grievances of 19 senators in the country's upper parliament in regard to the constitutionality of the treaty in the country.

Czech President Vaclav Klaus said earlier he would not sign the ratification until the Constitutional Court made a decision, citing it as a threat to the country's national sovereignty in its current form.

He demanded, among other things, an opt-out for his country from the EU Charter of Fundamental Rights over fears of property claims by Germans expelled after WWII and asked the Czech Constitutional Court to review the treaty to see whether it conforms to the country's constitution.

The Lisbon Treaty is an international agreement signed in Lisbon on December 13, 2007 which is expected to change the workings of the European Union. Only the Czech Republic has so far refused to ratify the document, which needs the approval of all 27 EU members to take effect.