All 27 members states must ratify the treaty before it becomes law
An attempt to block Britain's ratification of the Lisbon Treaty has been rejected by the High Court.
Conservative MP Bill Cash sought a judicial review of the ratification process after Ireland rejected the treaty in a referendum.
He said it would be unlawful for the UK government to continue with it.
But in a ruling, Mr Justice Collins said: "It will be for Parliament, not the court, to decide whether the Bill should be passed."
He said ratification was "a matter of political not judicial decision" and Mr Cash's case was "totally without merit since it is an attempt to pursue a political agenda through the court".
Mr Cash said he was now considering whether to pursue the case further by seeking an oral hearing in court.
He described the government's decision to continue to ratify the treaty as "disreputable" due to the "legally binding" nature of the Irish vote.
He said: "Even Tony Blair as prime minister abandoned the original European Constitutional Treaty Bill when the French and the Dutch voted 'No' because he knew that that Treaty could not be ratified".
He said the same principle should be applied to the Lisbon Treaty.
Business tycoon Stuart Wheeler is, meanwhile, still awaiting a High Court verdict on his attempt to force a referendum on the Lisbon Treaty.
Mr Wheeler argued that he had a "legitimate expectation" there would be a public vote after one was promised by Labour on the constitutional treaty.
Judgement was reserved after a two day hearing earlier this month but a decision was pledged "as soon as possible".
The UK has now effectively ratified the EU's reform treaty, with it gaining Royal Assent on Thursday.
The final stage of the process is when the government deposits the articles of ratification in Rome - the treaty will not come into force until all 27 EU member countries have done the same.
A Foreign Office spokeswoman said that it could be "several weeks" before that happens - but said it would happen before the summer recess in late July.
A last-ditch Tory bid to delay the ratification process for four months was defeated by a margin of 93, and peers later gave the EU Amendment Bill a third reading.
The ruling came as European Union leaders travelled to meet in Brussels to discuss the crisis caused by the Irish "No" vote.
European Commission President Jose Manuel Barroso thanked the British government for its "constant support" for the new treaty - and he urged all other EU states who have yet to approve the document to continue the process despite Ireland's no-vote.
"I believe the new treaty will make the EU more effective, democratic and stronger on the global stage," he said. "The treaty of Lisbon has now been approved by 19 member states.
"I call on all of those that have not ratified the treaty to continue the ratification process."
Europe minister Jim Murphy said the British government "still believes this is a good treaty and helps to modernise the European Union".
"The EU can ill-afford another period of introspective, circular discussion about our structures... that, bluntly, turn so many people off," he added.
But UKIP leader Nigel Farage, who campaigns for Britain's exit from the EU, said President Barroso's "EU nationalism" was the "most dangerous political phenomenon to have swept Europe since 1945".