Catalonia's President Artur Mas has been placed under formal investigation for his role in the Spanish region's unofficial vote on independence.
Catalonia's High Court said it would open proceedings against Mr Mas for allegedly disobeying a constitutional ban against the vote.
The 9 November vote, which was not binding, went ahead despite fierce opposition by the Spanish government.
Catalan officials say more than 80% of those who voted backed independence.
Mr Mas, his deputy Joana Ortega, and Catalan Education Minister Irene Rigau face accusations ranging from disobedience and perverting the course of justice to misuse of public funds.
'Right to a referendum'
Catalonia is one of Spain's richest and most highly-industrialised regions, and also one of the most independent-minded.
With a distinct history stretching back to the early Middle Ages, many Catalans think of themselves as a separate nation from the rest of Spain.
Earlier this year, the Spanish government appealed against the autonomous north-eastern region's plans for a referendum, and Spain's constitutional court suspended the vote and ordered a ban on campaigning.
The Catalan government reacted by making the vote unofficial and non-binding, and gave the task of organising the ballot to thousands of volunteers.
Some 2.3 million people took part in November's ballot, out of an electorate of 5.4 million. Mr Mas called the poll "a great success" that showed the region had "earned the right to a referendum".
However, the Spanish government dismissed the exercise as a "useless sham" and Prime Minister Mariano Rajoy stressed that most voters had not taken part.