BANGKOK — It has become almost routine in Thailand for judges to hand down jail sentences to those convicted of offending the country’s king. But an unusual ruling issued on Thursday appears to considerably broaden the interpretation of Thailand’s already restrictive lèse-majesté law.

In sentencing a former protest leader to two years in prison, a court ruled that the defendant was liable not only for what he said, but also for what he left unsaid.

The criminal court’s ruling said the defendant, Yossawarit Chuklom, had not specifically mentioned the king when he gave a speech in 2010 to a large group of people protesting the military-backed government then in power.

But by making a gesture of being muzzled — placing his hands over his mouth — Mr. Yossawarit had insinuated that he was talking about the king, the court ruled.