A former Catalonian vice-president, a former cabinet minister and two civic group leaders have been refused bail by Spain's highest court.
Oriol Junqueras, Joaquim Forn and and Jordi Sanchez and Jordi Cuixart, the leaders of Asamblea Nacional Catalana (ANC) and Omnium Central, face charges of sedition.
Why did the court decide this?
The Supreme Court judge ruled that, while he considered there was no risk the defendants would leave the country, he did believe there was a risk of criminal reiteration.
Campaigning for the election, with Junqueras at the head of the list for his ERC party, begins on Tuesday. Polls have shown that support for independence is running in a dead heat with support for continued unity with Spain.
Six other former members of the Catalonian cabinet have been set bail of 100,000 euros.
They were all detained in custody ahead of an investigation into their part in an illegal unilateral declaration of independence in October by the then-regional government.
The Catalonian leaders' organisation of an independence vote on October the 1st and subsequent declaration of independence have tipped the country into its worst political crisis in more than four decades.
Both acts are banned under the Spanish constitution.
The central government sacked the previous government within hours of the declaration and called a regional election for December 21.
The eight former members of the cabinet were detained in custody on November the 2nd on charges of sedition, rebellion and misappropriation of funds.
They have since called to be released to campaign for the election.
What has happened to the rest of the government?
Carles Puigdemont and four of his disbanded cabinet are in self-imposed exile in Belgium.
They are under conditional release after an international arrest warrant was served against them.
The eight former members of the cabinet were detained in custody on November 2 with potential charges of sedition, rebellion, and misappropriation of funds.
They have called to be released to campaign for the election.
Campaigning for the election begins on Tuesday, December 5, with Junqueras as the head of his party, Republican Left of Catalonia.
AFP reported that Belgian judges will rule on Puigdemont's extradition on December 14.