The Spanish government sees constitutional order in Catalonia recovering after former speaker of the Catalan regional parliament, Carme Forcadell, accepted the application of Article 155 appearing in a Spanish court on Friday.
The deposed Catalan president, Carles Puigdemont, went into self-imposed exile in Belgium last week after Spain's central government responded to an independence declaration by firing his administration, dissolving the Catalan parliament and calling regional elections for December.
Forcadell, a leading Catalan independence figure, and five other lawmakers were quizzed in a rebellion investigation following the Catalan parliament's October 27 secession declaration.
Also today, the High Court rejected an appeal presented by their lawyers for their release, a court spokeswoman said.
Eight members of the Catalan government who were tried in the High Court are in pre-trial detention, without the possibility of bail.
Puigdemont at the time called the declaration a major step toward establishing an independent Catalan state, and Forcadell described Rajoy's response as a coup and an "attack against democracy".
The Catalan independence push has deeply divided Spain, dragging it into its worst political crisis since the return of democracy four decades ago and fuelling anti-Spanish sentiment in Catalonia and nationalist tendencies elsewhere. The vote, however, suffered from turnout of 43% and had been declared "illegal" by the Spanish Constitutional Court before any votes were cast.
The struggle has also divided Catalonia itself, and cracks have begun appearing within the pro-independence movement.
The five, and one other who was released, had been quizzed in the rebellion investigation following the Catalan parliament's October 27 secession declaration.
"Citizens supporting an idea of independence is legitimate", Judge Llarena wrote.
Court sources had quoted Forcadell and other summoned Catalan lawmakers as telling the judge that the independence declaration had not been legally binding - comments that the Spanish government welcomed on Friday.
The Spanish Supreme Court's decision comes in contrast to recent rulings made by the Spanish High Court.
This story was reported by Reuters.