Once that happens, the Lisbon Treaty will allow more policy decisions by majority rather than unanimous votes at European summits. Those policies would then increasingly be shaped by the elected parliaments of each nation and the European Parliament, which now has little say.

EU leaders say such new voting rules are needed to promote stronger policies in combating cross-border crime, terrorism, and ecological threats.

Projecting this more decisive EU abroad would be a new fixed-term president - in place of a decades-old system that rotates the presidency among governments every six months - and a new foreign minister.

That all became possible when Czech President Vaclav Klaus, who has been highly skeptical of increasing the EU's powers, signed the Lisbon Treaty at the Prague Castle yesterday, hours after his nation's Constitutional Court struck down a complaint against it.

Klaus had been tirelessly attacking and stalling the document, contending it would hand too much power to EU institutions in Brussels, Belgium. He was awaiting the court's ruling before deciding whether to endorse the treaty.

"I expected the decision of the Constitutional Court and respect it," Klaus said yesterday afternoon, but he added that he vehemently disagreed with the verdict.

Once the treaty enters into force, "the Czech Republic will cease to be a sovereign state," he said.

Klaus was the last obstacle to full ratification of the treaty, which was bogged down in negotiations for almost a decade and has been ratified by all 26 other EU nations.

The Swedish EU presidency said the treaty would enter into force Dec. 1.

European leaders welcomed news of the signing.

Klaus' decision "marks an important and historic step for all of Europe," British Prime Minister Gordon Brown said in a statement.

German Chancellor Angela Merkel noted during a speech to the U.S. Congress yesterday that, with the new treaty, the EU "will become stronger and more capable of acting, and so a strong and reliable partner for the United States."