Thailand’s Constitutional Court is set to rule on Wednesday whether the progressive Move Forward Party (MFP) violated the constitution when it pledged to amend the country’s lese-majeste law outlawing criticism of the royal family.

Should the court rule against the MFP, the party could be dissolved and its leaders banned for 10 years, marking a sharp turnaround in its fortunes since its stunning election victory a little more than a year ago.

Back then, millions of young Thais banded behind the MFP’s charismatic leader Pita Limjaroenrat, galvanised by the party’s promise of change. Its flagship policy was to reform Section 112 of Thailand’s Criminal Code, which restricts all criticism of the monarchy.

The party’s victory and reform agenda placed it firmly in the sights of Thailand’s long-ruling conservative elite. Pita was blocked from becoming prime minister and forming a government.

With tomorrow’s ruling set to define Thai democracy for years to come, here’s everything you need to know about the case:

What has led MFP to this point? 

MFP is the de facto successor to the Future Forward Party (FFP), which stormed to third in Thailand’s 2019 general election on an anti-junta platform, rocking the country’s ruling class.

After initially surviving a Constitutional Court case accusing it of attempting to overthrow the monarchy, the FFP was disbanded in February 2020 after it was ruled to have violated election finance laws by accepting a loan from its leader Thanathorn Juangroongruangkit.

Following the ruling, 55 of the FFP’s 65 members of parliament joined the MFP, promising to continue their progressive agenda. One such policy ahead of last May’s election saw the MFP pledge to amend Section 112, reducing the maximum prison term for defaming the king from 15 years to one year and/or a fine of 300,000 Thai Baht (about $8,400).

It was on this platform that the MFP secured a shock election victory in 2023, winning 151 seats in Thailand’s 500-seat House of Representatives, 10 more than Paetongtarn Shinawatra’s second-placed Pheu Thai party.

The MFP, however, fell short of the 251 seats required for an outright majority, with attempts to form a coalition with other pro-democracy parties, including Pheu Thai, blocked by Thailand’s military-installed Senate using power handed to it by a 2017 military-drafted constitution.

In July, the Constitutional Court suspended Pita as an MP over shares he allegedly held in a defunct broadcaster – charges he was later acquitted of. Pheu Thai successfully formed its own coalition, incorporating military-aligned parties and excluding the MFP.

In January this year, the Constitutional Court ruled that the MFP’s proposed lese-majeste amendments amounted to a violation of Section 49 of the constitution, which prohibits attempts to “overthrow the democratic regime of government with the King as Head of State”.

It ordered the party to “stop any act, opinion expression via speech, writing, publishing or advertisement or conveying any message in other forms” that sought to amend Section 112.

What is the court set to rule on now? 

In March, the Constitutional Court agreed to review an Election Commission submission requesting that the MFP be dissolved and its leaders be banned from participating in politics for 10 years over Section 112. The commission justified its request by pointing to the court’s January ruling, saying there was “evidence that Move Forward undermines the democratic system with the king as the head of state”.

MFP argued in a written defence submitted on June 4 that the court lacked jurisdiction and the commission’s petition process was unlawful. It argued, among other things, that the MFP had no intention to overthrow the system, dissolution should be a last resort, and any political ban should be proportionate and targeted to specific MFP members.

Patrick Phongsathorn, a senior advocacy specialist at Thailand-based human rights NGO Fortify Rights, said the commission was “compromising its own political neutrality and independence” by bringing this case against the MFP.

“This case seems to be politically motivated and follows a general pattern where the Thai establishment seeks to silence increasingly popular opposition parties,” he told Al Jazeera.

Experts hold little hope that the MFP will win a reprieve. With a precedent set by the FFP’s dissolution in 2020, and the court’s January ruling against the MFP, Mark S Cogan, an associate professor of peace and conflict studies at Japan’s Kansai Gaidai University, whose research focuses on authoritarian regimes in Southeast Asia, said the “writing is on the wall”.

“The Constitutional Court has already signalled earlier this year where it is going,” he told Al Jazeera. “The Constitutional Court, an institution with a history of political party dissolution, declared in January that Article 112 reform was treasonous, so what other message could it now send?”

What happens next? 

The nine-member Constitutional Court will convene on Wednesday at 9.30am local time (02:30 GMT) and read its decision at 3.30pm (07:30 GMT).

Like 2020’s youth-led demonstrations following the FFP’s dissolution, Cogan predicts there will be protests should the MFP be dissolved, although the scale may be hard to predict.

“The protests will be given plenty of space by [Prime Minister Srettha Thavisin], who failed to come to Pita’s defence and who arguably dissolved Pheu Thai’s credibility within Thailand’s democratic movement when it agreed to a majority government with military and monarchy-aligned parties,” he said.

While Phongsathorn said any move to dissolve the MFP would be just the latest in a “broader pattern” in Thailand of “weaponising the judiciary against political opposition”, the case is “more significant” given the party’s huge popularity.

But even if the MFP were to be dissolved, Phongsathorn says, the “progressive genie is now out of the bottle and will be very hard to put back in”.

As the FFP was replaced with the MFP, so “some other party will be established to represent the views of this evolving social movement”, he said.

For his part, former MFP leader Pita is presenting an optimistic public message to his supporters, urging them not to lose hope regardless of the outcome.

He will be present in court when the ruling comes down.

“We’re fighting this not just because of my personal future or my party’s future, but we want to make sure that, if it happens, that Pita becomes the last person, the Move Forward Party becomes the last party, that joins the graveyard of political parties,” he told the Associated Press news agency.