EU:GERMAN PRESIDENT Horst Köhler has suspended ratification of the Lisbon Treaty at the request of the constitutional court.
A second challenge to the Lisbon Treaty was lodged with the court last week, suggesting it may be some time before they are able to deliver a ruling.
The announcement adds a new twist to EU plans to rescue the Lisbon Treaty following Ireland's No vote.
At last month's summit in Brussels, chancellor Angela Merkel and other EU leaders pushed for ratification to continue and be completed by the end of the year.
That would have increased the political pressure on Ireland, as the only country not to have ratified.
But legal experts in Berlin said yesterday it was now less likely that Germany would be able to ratify by the end of the year.
Mr Köhler's office issued a statement yesterday that he would not sign the ratification Bill, already approved of by both houses of parliament, after "a request from the constitutional court".
Without his signature, the Bill cannot come into force. German government spokesman Ulrich Wilhelm said Mr Köhler's decision was "understandable" and reflected the procedure with earlier EU treaties. Berlin government sources yesterday said there was no reason to assume it would take longer for a verdict.
Government politicians were less confident. The Social Democrat EU affairs spokesman, Axel Schäfer, said Mr Köhler's decision "sends the wrong signal" and was "grist to the Eurosceptics' mill".
It is not the first time that Mr Köhler has demonstrated his political independence by refusing to sign a new Bill. However, it is the first time such a decision has EU-wide implications.
Former president Roman Herzog signed the Maastricht Treaty ratification Bill before sending it to the constitutional court for closer examination.
German ratification of the now defunct constitutional treaty was delayed by a court challenge and eventually abandoned after its rejection by French and Dutch voters. Bavarian MP Peter Gauweiler was behind the constitutional treaty challenge and has lodged another challenge to the Lisbon Treaty. Last week the Left Party followed suit, saying Lisbon curtailed the rights of the German parliament.