The Supreme Court on Friday overruled an Appeals Court ruling and acquitted former deputy prime minister Suthep Thaugsuban, now a monk, of libelling Prommin Letsuridej, former executive of the now-defunct Thai Rak Thai Party in 2006.
The court also upheld the prior acquittal of former prime minister Abhisit Vejjajiva and Ong-art Klampaibul of the Democrat Party on similar charges.
Mr Prommin filed a lawsuit against the three men for a remark Mr Suthep made at a press conference on March 16, 2006 -- that Mr Prommin was among the Thai Rak Thai executive members who committed poll fraud by hiring small parties to run in the April 2, 2006 election.
The Supreme Court found that Mr Suthep had no ill intention when he made the remark, and dismissed the suit.
In June 2009, the Criminal Court dismissed the case in the first instance, ruling Mr Suthep was only citing filmed conversations when he made the comment. The plaintiff appealed.
In September 2012, the Appeals Court decided that Mr Suthep should have screened and analysed the information before making it public.
It found him guilty of defaming Mr Prommin and handed down a suspended four-month jail sentence, and fined him 2,000 baht.
The court upheld the lower court's decision to acquit the other defendants, namely the Democrat Party, Mr Abhisit, who was not present at the press conference, and Mr Ong-art, who said nothing about the fraud at the press conference.
The Democrat Party and two other political parties had boycotted the April 2, 2006 poll and encouraged voters to do the same.
The poll followed then-prime minister Thaksin Shinawatra's decision to dissolve the House on Feb 24, 2006, just before a censure debate amid several heated political issues and corruption allegations.
The Constitutional Court later nullified the April 2 poll. The reasons included the hiring of small parties to pretend to compete in the election to legalise victory for Thai Rak Thai candidates in many constituencies.