Media playback on your device is not supported Independence protesters: "We all feel court-ordered"
The verdict of Monday comes after four-month hearings.
During their final clashes in June, defense attorneys told the court that their clients had rejected the allegations of sedition and sedition, but acknowledged that they had been less indicted for disobedience.
Who are the 12 Catalan leaders?
Some had prominent positions in the Catalan government and Catalan parliament, others were influential activists and cultural lawyers.
Before the end of the trial, the 12 defendants each had 15 minutes to present their arguments to the prosecutor on the last day of June 12.
They told the Madrid court they were victims of injustice in a trial based on "false" allegations:
What they said in their defense
Oriol Junqueras former vice-president of Catalonia: " Voting and defending the republic in front of a parliament can not be a crime. "
Jordi Cuixart President of the Catalan Language and Culture Organization Òmnium Cultural: "What we did on October 1 [holding the 2017 referendum] was an exercise of collective dignity."
Carme Forcadell Former Speaker of the Catalan Parliament: "I have not participated in any strategy, but limited myself to performing my duties as Speaker of Parliament."
Jordi Turull former Catalan government spokesman: "We did not want to involve people [in the bid for independence] who already existed, and so a political solution had to be found. "
Joaquim Forn Former Catalan Minister of the Interior: "I defended the referendum as a politician, but called on the Catalan police to obey orders."
Jordi Sànchez Activist and former President of the Catalan National Assembly: "I am a victim of injustice – there are no ideas or principles that should be silenced."
Raül Romeva Former Foreign Minister: "There is no international treaty that prohibits the right to self-determination Spanish Constitution. "
Dolores Bassa Former Minister of Labor:" It was always clear to us that negotiating would help us if many people stood for election [with Madrid]. "Independence was always viewed as consensual. "
Josep Rull Former Territorial Minister:" People are voting and it's good that the parties deliver … ours Manifesto was not challenged in court.
Carles Mundó former Minister of Justice: "The vote was not paid from public funds, I saw [it] as a political protest."
Meritxell Borràs Former Minister of State: "[The vote was] a political Expression [that] had no legal consequences.
Santi Vila former Minister of Economy: "I saw the referendum as a political protest.
Nine of the defendants had already spent months in custody The remaining three were released on bail earlier.
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Carles Puigdemont, the former Catalan president, escaped trial in late October 2017 after escaping from Spain before he was arrested along with four others.
How did they end up in court?
The prosecution argued that the unilateral Declaration of Independence was an attack on the Spanish state, and accused some of those involved in a serious uprising.
They also said that the separatist leaders at the org the referendum in 2017 would have misused public funds.
The prosecutors argued that the leaders had a "perfectly planned strategy … to break that" carried out constitutional order and to gain Catalonia's independence "illegal.
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Forcadell As a result, on October 27, 2017, the former parliamentary speaker, who was accused of independence, was accused of having admitted parliamentary debates on independence despite warnings from the Spanish Constitutional Court.
Some of the leaders before the trial with the BBC All the violence, they said, had been perpetrated by police and voters, making headlines around the world.
Three weeks after the 2017 banned poll, Catalan declared that Parliament an independent republic.
Madrid resigned to the region to impose their rule, fled several Catalan leaders or were arrested.
What is behind the controversy surrounding Catalonia?
Catalan nationalists have long complained that their region has a strong history dating back nearly 1000 years, sending too much money to poorer parts of Spain, as taxes are controlled by Madrid.
The wealthy region is Here live about 7.5 million people with their own language, their own parliament, their own flag and their own anthem.
In September, a march in Barcelona to support the independence of Catalonia from Spain attracted a crowd of about 600,000 people. One of the lowest voter turnouts in the eight-year history of the annual rally.