The court upheld a criminal court conviction of Daranee Charnchoensilpakul, 50, on three counts of lese majesty in a public speech she delivered at a political rally in 2008.
"She has set a bad example for other people," the court said. Daranee, better known by her nickname Da Torpedo for her fiery political oratory, said she would appeal to the Supreme Court.
"I want my case to get as much public exposure as possible," she said.