A man was sentenced on Wednesday to two years in jail for selling books deemed to have defamed the monarchy.
The Court of Appeal overturned a 2014 judgement that had cleared Udomsak Wattanaworachaiwathin of any wrongdoing in a case which stretches back nine years.
A request for bail, pending a further appeal, was set to be heard later today.
The 66-year-old was initially arrested in May 2006 for selling two books that allegedly violated the lese majeste law during a protest in a downtown Bangkok park.
Prosecutors did not file charges against him until seven years later, according to iLaw, a local legal group that monitors Thailand's lese majeste cases.
A criminal court dismissed the charges in March 2014 after ruling that the prosecution had failed to prove that Udomsak knew the content of the books was defamatory of the monarchy.
Prosecutors then appealed the ruling, resulting in Wednesday's conviction.
"The defendant's behaviour has shown that he knew the book had insulting details about the monarchy, and he could not prove the two copies he sold belonged to other people as he had claimed," the judge told the court.
The judge said she decided to reduce the sentence from three to two years because of "useful testimony" by Udomsak.
Under Section 112 of Thailand's criminal code anyone convicted of insulting the King, Queen, heir or regent faces up to 15 years in prison on each count.
Earlier this month a military court imprisoned a 58-year-old man for 25 years for a series of Facebook posts that were ruled to have defamed the monarchy, a sentence that received widespread international condemnation including from the UN.
Udomsak, a grey-haired man dressed in a long-sleeved shirt, showed no emotion as the ruling was read out. His lawyer, Yaowalak Anuphan, said they would appeal to the Supreme Court.
"We are confident he is innocent, he really had no idea about the (contents of the) book," she told AFP.
