Spain's Supreme Court has ordered a retrial of the leader of the banned Basque Batasuna party, after overruling his conviction for promoting terrorism.
Arnaldo Otegi will be retried before a new panel of judges
The court ruled that Arnaldo Otegi, who was facing a 15-month prison sentence, had not received a fair trial.
He was convicted for praising fallen Basque militants at a funeral in 2001.
The appeal ruling came after a court banned a Batasuna rally on Saturday. Batasuna was banned from politics in 2003 over alleged links to Eta.
Mr Otegi was convicted in 2004 for his part in the funeral of Basque separatist Olaia Castresana, who died after explosives she was handling blew up.
At the burial, Mr Otegi offered his "warmest praise to all gudaris (Basque soldiers) who have fallen in this long fight for self-determination".
The Supreme Court ruled on Wednesday that the judgement had not been impartial and ordered a Basque court to retry Mr Otegi before a new panel of judges.
A High Court judge ordered a new two-year ban on Batasuna's political activities, saying that it was controlled by armed separatists.
Batasuna has always denied being the political wing of Eta but has refused to condemn attacks by the group.
Mr Otegi kept his seat in the Basque regional parliament after the party changed its name.
He lost his MP's immunity from prosecution last year when Batasuna candidates were barred from standing in April's regional elections.
He spent four years in jail for kidnapping in the 1980s.