The German Constitutional Court has ruled that critical powers of the German parliament are usurped by the Lisbon Treaty and that the country’s constitution must be changed before the treaty is ratified.

The Court ruling today said that the German constitution had to be changed to ensure that both houses of the German parliament, the Bundestag and Bundesrat, were not overridden by the decisions taken in Brussels.

These two legislative bodies had to have a say in the making of laws in Brussels, the court ruled.

The ruling confirms the long held British National Party position on the Lisbon Treaty which is that that agreement undermines national sovereignty and will see legislative power removed from all national parliaments and transferred to the EU.

Although the media are attempting to put a positive spin on the court’s ruling by highlighting the fact that the Lisbon Treaty will go ahead once the constitutional changes have been made, the reality is that if the amendment fails in the German parliament, the treaty will be dead.

Germany is one of the EU’s most powerful constituent states and at least 50 members of its parliament are known to be strongly opposed to the treaty.

The court’s ruling specifically called a halt to the ratification process until the German parliament makes the necessary changes. Specifically, the court ruled, the existing law which regulates the German parliament’s involvement in the implementation of European law needs to be strengthened before the ratification process can continue.

“It demands a strengthening of the parliament’s responsibilities on a national level,” said presiding judge Andreas Vosskuhle.

Germany is one of four countries that has still not ratified the Lisbon Treaty, which is in essence identical to an earlier constitution rejected by the voters of France and the Netherlands in 2005.

Ireland rejected the treaty in a referendum last year and euro-sceptic presidents in the Czech Republic and Poland have refused to rubber-stamp approval of the constitution.

One of the strongest critics of the Lisbon Treaty is Mr Peter Gauweiler, a member of Bavaria’s Christian Social Union (CSU) in the German Bundestag. The CSU is the sister party to Chancellor Angela Merkel’s ruling Christian Democratic Party. Mr Gauweiler is also the chairman of the sub-committee on foreign cultural and educational policies of the Foreign Affairs Committee of the German Bundestag, and was one of the principal appellants in the motion which led to the recent German Constitutional Court challenge.

Mrs Merkel is strongly in favour of the Lisbon Treaty, and a falling out with Mr Gauweiler could provoke a parliamentary crisis for the ruling party. The German parliament is to gather for a special sitting on 26 August for a first reading of the new law. The vote in the lower house would then take place on 8 September, just weeks before Germany’s national election.