The Appeals Court on Tuesday upheld the lower court's sentence of a 12-month prison term for former red-shirt leader Arisman Pongruangrong for defaming former prime minister Abhisit Vejjajiva.
Arisman was found guilty of defaming Mr Abhisit during speeches on a stage on Oct 11 and Oct 17, 2009 at the Democracy Monument and in front of Government House.
His speeches were broadcast live on satellite television station People Channel.
The Criminal Court sentenced Arisman to 12 months in jail without suspension.
Arisman appealed, seeking a lighter sentence and a suspension of the prison term.
The Appeals Court found no reason to reduce or suspend the sentence, and upheld the lower court's decision.
Arisman was later released on 500,000 baht bail.