BANGKOK (AP) — The former leader of Thailand’s progressive opposition Move Forward party vowed on Sunday to keep fighting as the party faces a court case that could result in its dissolution.

The Constitutional Court has agreed to rule on whether the party violated the constitution by proposing to amend a law that forbids defaming the country’s royal family. The petition requested the party’s dissolution and a 10-year ban on political activity by its executives. The court has not said when it will rule on this case.

Pita Limjaroenrat, the former leader of Move Forward, laid out the details of the party’s legal defenses that have been submitted to the court at a news conference on Sunday.

“If there is a rule of law in Thailand, I’m extremely confident” the party’s arguments will prevail, he said.

Pita said the Constitutional Court does not have jurisdiction to rule on this case and that the petition filed by the Election Commission did not follow due process because Move Forward was not given an opportunity to defend itself before the case was submitted to the court.

The petition was filed after the same court ruled in January that the party must stop advocating changes to the law, known as Article 112 in Thailand’s criminal codes, which protects the monarchy from criticism by imposing penalties of three to 15 years in jail per offense.

That ruling did not set any punishment for the party.

Move Forward shook up Thai politics by winning the most seats in the general election last year but was blocked from taking power and has since been fighting several legal battles to keep its positions in Parliament. These legal cases are seen as part of a yearslong attack against the country’s progressive movement by conservative forces trying to keep their grip on power.

Move Forward’s predecessor, the Future Forward party, was dissolved by the Constitutional Court in 2020 for violating election laws on donations to political parties.

Move Forward has insisted that it wants to keep the monarchy above politics and not be exploited as a political tool.

Thailand’s monarchy is considered untouchable but student-led pro-democracy protests, triggered by the dissolution of Future Forward in 2020, began to challenge that sentiment by openly criticizing the monarchy. That led to vigorous prosecutions under the law, which critics say is often used as a tool to quash political dissent.

The advocacy group Thai Lawyers for Human Rights says that since early 2020, more than 270 people have been charged with violating Article 112. Some of those are Move Forward’s own lawmakers.

Thailand’s courts, especially the Constitutional Court, are considered a bulwark of the country’s traditional royalist establishment, which has used them and nominally independent state agencies such as the Election Commission to issue rulings to cripple or sink political opponents.

Pita warned that getting rid of the country’s largest opposition party would mean “an attack on democracy” as it would weaken the mechanism of checks and balances on the government.

“The strength of democracy is not about how robust the government is, but how fair and active the opposition is,” he said.

The Move Forward party finished first in the 2023 general election after campaigning to amend Article 112 and introduce other democratic reforms. The victory indicated that many Thai voters were ready for change after nearly a decade of military-controlled government.

But the military-installed Senate blocked the party from taking power by refusing to confirm Pita, who was the party's candidate for prime minister. Senators said they opposed Pita because of his intention to enact reforms to the monarchy.