A court in Thailand on Wednesday ordered the dissolution of the progressive Move Forward Party, which won national elections in 2023, saying it violated the constitution by proposing an amendment of a law against defaming the country’s royal family.

The Constitutional Court said it voted unanimously to dissolve the party because its campaign to amend the law was considered an attempt to overthrow the nation's constitutional monarchy.

The Election Commission filed a petition against the Move Forward Party after the Constitutional Court ruled in January that it must stop advocating changes to the law, known as Article 112, which protects the monarchy from criticism with penalties of up to 15 years in jail per offense.

The ruling also imposed a 10-year ban on political activity on those who held the party’s executive positions while it campaigned for the proposed amendment. Among them are its charismatic former leader, Pita Limjaroenrat, and current chief Chaithawat Tulathon.

It remained unclear what will happen to the rest of its non-executive lawmakers, although Pita said in an interview with The Associated Press that the party will ensure they have a “smooth transition into a new house,” or a new party.

Lawmakers of a dissolved political party can keep their seats in Parliament if they move to a new party within 60 days.

Move Forward and its reform agenda shook up Thai politics by winning the most seats in the 2023 elections but was blocked from taking power. The latest legal action is one of many that have drawn widespread criticism and are seen as part of a yearslong attack on the country’s progressive movement by conservative forces trying to keep their grip on power.