The head of Spain's Catalonia region, Artur Mas, has vowed to go ahead with a symbolic vote on independence on Sunday in defiance of a court ban.
"All peoples have the right to decide their future," Mr Mas said, explaining his decision to continue with the vote.
Spain's constitutional court ordered the regional government to suspend the planned vote on Tuesday.
It is the latest in a string of legal challenges lodged by the Spanish government, which opposes the vote.
Mr Mas vowed to hold an informal vote after the constitutional court suspended earlier plans for a non-binding referendum on secession in September.
Catalonia's regional government had dubbed the vote a "consultation of citizens" in the hope of circumnavigating the suspension.
But the constitutional court blocked moves to hold the vote again this week, in order to hear the government's case, a process that could take months.
Determined to press ahead with the poll, Mr Mas said in a speech on Wednesday: "We are defending fundamental rights protected by basic laws: Freedom of conscience; freedom of participation and freedom of expression."
The regional authorities acknowledge the vote will only have symbolic significance, with Mr Mas insisting it should not be called a referendum.
Experts have warned that they will be breaking constitutional law by carrying out the symbolic vote. It is not yet clear how the central authorities in Spain will respond if it goes ahead.
Thousands of volunteers have been recruited by the regional authorities to run the vote, which will have no formal electoral roll.
Economic and cultural grievances have fuelled Catalan nationalism.
The wealthy region of 7.5 million people contributes more to the Spanish economy than it gets back through central government funds.
Like other Spanish regions, it enjoys a degree of autonomy but campaigners accuse Madrid of recently seeking to undermine Catalan in favour of Spanish as the main language of instruction in schools.