A formal investigation has been opened into the role Catalan President Artur Mas played in the unofficial independence vote in Catalonia.
Catalonia's High Court said the proceedings were against Mr Mas for allegedly disobeying a constitutional ban against the vote.
Sr 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.
The vote was fiercely opposed by the Spanish government but went ahead anyway on 9 November although it was down-graded to a non-binding consultation rather than a referendum.
Catalan officials say more than 80% of those who voted backed independence.
But the Spanish government called the exercise as a "useless sham" and Prime Minister Mariano Rajoy said that most voters had not gone to the polls.
Some 2.3 million people took part in November's ballot, out of an electorate of 5.4 million.
A strong streak of independence runs through many inhabitants of the autonomous region, one of the most industrialised in Spain. The area generates a lot of wealth and some there resent the funding it provides to central government.
