The Eurosceptic Czech president opposes the treaty
A top Czech court has said the EU's Lisbon Treaty is compatible with the country's constitution.
The parliament's ratification of the controversial reform treaty was halted earlier this year pending the ruling by the Constitutional Court.
The Czech Republic is among a handful of countries that have not yet ratified the treaty. It cannot take effect unless all 27 member states do so.
The treaty was dealt a heavy blow in June, when Irish voters rejected it.
Signed in December 2007, the treaty is aimed at streamlining decision-making in the enlarged 27-nation EU.
Next month the Irish government is expected to present ideas for resolving the deadlock created by the Irish No vote. The No lobby insist there can be no re-run of the June referendum and that "no means no".
Czech President Vaclav Klaus has argued that the treaty would undermine Czech sovereignty.
The Czech court ruling on Wednesday is especially significant because the Czech Republic will take over the six-month rotating EU presidency in January.
"The Lisbon Treaty... does not run counter to the constitutional order," said court chairman Pavel Rychetsky.
But the treaty's passage through the Czech parliament may not be smooth, as some Eurosceptic members of Czech Prime Minister Mirek Topolanek's party oppose it. Mr Topolanek has said ratification is unlikely to be completed before next year.
The court did not consider the treaty as a whole, but only the articles disputed by critics in Mr Topolanek's party.
The treaty was originally meant to be in place in January 2009, well ahead of the European Parliament elections in June 2009.
Critics see the treaty as further evidence of a federalist, pro-integration agenda at work in the EU. They say the treaty is just a modified version of the EU constitution, rejected by French and Dutch voters in 2005.
Even some of the architects of the defunct constitution say that the Lisbon Treaty is very similar to it.
One of them, Labour MP Gisela Stuart, says the Lisbon Treaty "is to all intents and purposes the old EU constitution under a different name".
Poland's President Lech Kaczynski has delayed signing the treaty until the deadlock over the Irish No vote is resolved.