A top court in Thailand ordered the country’s main opposition Move Forward Party to cease all attempts to amend the country’s stringent royal insult law, a centerpiece of its reformist agenda that helped it win last year’s election.

The Constitutional Court on Wednesday ruled that the party’s campaign to loosen Article 112, known as lese majeste law, violated the charter. The nine-member court said in a unanimous ruling that Move Forward’s push for changes amounted to an attempt to overthrow the constitutional monarchy.

The reformist party and its prime minister candidate Pita Limjaroenrat covertly pushed an agenda to "destroy” the form of government with the king as head of state, under the guise of a proposal to amend the controversial law, the court said.