A 67-year-old man caught writing graffiti on a toilet wall at a mall in Bangkok last year was sentenced to one year and six months in prison for lese majeste by the Bangkok Military Court on Friday.
Opas Chansuksai, 67, was initially given three years in jail, but the sentence was halved because he confessed to the charge.
Observers said it is the first time the Military Court has given such a light punishment for lese majeste. Representatives of the United Nations, foreign media and relatives of the defendant were allowed to hear the judgement.
Mr Opas was caught on Oct 15 last year by security guards at Seacon Square shopping centre who found him writing on a toilet wall.
The mall's management fined him 2,000 baht for damaging its property, and then called soldiers to arrest him.
During interrogation, Mr Opas told police he was left depressed by the actions of the government and the earlier political protests. He had also listened to some political community radio programmes, which added to his depression.
His lawyer had earlier submitted four requests for his temporary release on bail, citing ill health. They were all rejected.