Mr Wheeler said voters had a "legitimate expectation" of a vote
Millionaire Stuart Wheeler has won his battle to force a High Court review into whether the government should hold a referendum on the EU's Lisbon treaty.
Prime Minister Gordon Brown has ruled out a public vote on the treaty, saying it does not alter the UK constitution.
But Mr Wheeler said a vote was promised on the EU constitution and says the Lisbon treaty is virtually identical.
The hearing will be on 9 and 10 June. The Foreign Office said they were "confident" of their case.
In March MPs voted by 346 votes to 206 to approve the EU (Amendment) Bill, after topic-by-topic debates over six weeks.
The Bill - which is now in the Lords - will ratify the Lisbon Treaty, which was drawn up to replace the EU constitution after that was rejected by French and Dutch voters in 2005.
Mr Wheeler, 73, a Conservative Party donor, said his legal challenge was "not trying to interfere with Parliament".
He claims voters had a "legitimate expectation" that a referendum would be held after one was promised in Labour's last election manifesto on the EU constitution.
His lawyer, Rabinder Singh QC, said the application for judicial review was based on "the underlying fundamental principles of good administration, fair play and straight dealing with the public".
But Philip Sales QC, for the office of the prime minister, denied that Gordon Brown or Foreign Secretary David Miliband had made any unambiguous and unqualified representation amounting to a promise to hold a referendum.
He also said the claim was "misconceived" as a ratification of an international treaty was not open to challenge in the High Court and would breach Parliamentary privilege.
But the judge rejected all of Mr Sales's arguments.
Speaking after the ruling, Mr Wheeler said: "I am absolutely delighted that we won the case. It's clear to me that we have a very, very strong moral case for a referendum."
Lord Leach, chairman of the Eurosceptic think tank Open Europe - of which Mr Wheeler is a member - said the ruling "renders the government's attempt to ratify the Lisbon Treaty sub judice".
He said he would raise the matter in the House of Lords where peers are debating the Bill and said the government should "stay its hand pending the outcome of this judicial review".
But a Foreign Office spokesman said the threshold for deciding whether a case was arguable at judicial review was low, so the decision was not a surprise.
"We are confident of the strength of our case on this occasion and look forward to putting our arguments before the court in more detail in due course," he added.
The High Court hearing will be heard on 9 and 10 June - the House of Lords is due to vote on calls for a referendum on 11 June.
All 27 EU countries will have to ratify the treaty before it can come into force.
The Conservatives have said that they would not ratify the EU treaty if they were to win the next election - which has to be held by May 2010.
The treaty contains many of the reforms outlined in the constitution - including changes to voting rights and the creation of a European Council president - but drops the name "constitution", a reference to EU symbols and an article on the primacy of EU law.