A judge who read out the verdict said there was not enough evidence to convict Yuthapoom Martnok. His brother Thanawat had been his only accuser, and other relatives had insisted Yuthapoom never insulted the crown.
Still, Yuthapoom was imprisoned for a year and denied bail on national security grounds. He will be freed later Friday.
Yuthapoom's wife, Jongkon Kongthin, welcomed the verdict but called the time apart from her husband "torture."
"We had to live without happiness," she said. "The court has mercy and this has proven that justice does prevail."
Critics said the case was worrying because it showed how easily Thailand's lese majeste laws could be abused.
The case was unusual not only because it pitted one brother's word against another, but because the alleged transgressions were said to have occurred in private, in their home.
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