Thai court set for divisive constitutional ruling By Amy Sawitta Lefevre BANGKOK (Reuters) - Thailand's Constitutional Court will decide on Friday whether government plans to amend the constitution are illegal, an outcome that could lead to the dissolution of the ruling party and bring its "red shirt" supporters onto the street. Even if the ruling goes in favor of the government, it could still open up another violent chapter in Thailand's seven-year political crisis because the powerful royalists oppose any change to a constitution enacted under a military-backed government in 2007. The government maintains its proposed changes are part of efforts to bring reconciliation to Thailand, altering a constitution seen by some as undemocratic. Opponents argue the changes will threaten the role of the monarchy and that one undeclared aim is to pave the way for former premier Thaksin Shinawatra to return from self-exile without serving time in jail for a graft conviction. Thaksin is the brother of Prime Minister Yingluck Shinawatra and is believed to be the real power behind her government, giving it orders from his villa in Dubai. A former telecoms billionaire, he is adored by the poor but reviled by the royalist establishment and military, which toppled him in a coup in 2006. The implications of any dissolution of Yingluck's Puea Thai are not clear-cut. Executives would be banned from politics but Yingluck and other ministers are not executives, so her government may be able to carry on, in the short term at least. A new party is already thought to have been set up and lawmakers could transfer into it, although the anti-Thaksin opposition might contest that. A court ruling against the amendments has the potential to spark protests around the country. A mass red-shirt rally effectively paralyzed central Bangkok in April and May 2010 before a military crackdown ended it after at least 91 people were killed in street violence. "I've consulted with red-shirt leaders in the northeast and we stand ready to gather at provincial town halls in the northeast provinces to show we won't accept a ruling against the charter change," Kwanchai Praipana, one of the movement's leaders, told Reuters. The pro-Thaksin red shirts heavily dominate the northeast of the country. Around 300 red shirts gathered near parliament in Bangkok late on Thursday and camped there overnight, warning they would not stand by if the court rejected the amendments. In a bid to calm the situation, Yingluck called on Thursday for all political groups to refrain from violence. She is due to fly to Cambodia for a regional conference on Friday, leaving just before the judges read their ruling from 2 p.m. (3.00 a.m. Yutthasak Sasiprapa, a deputy prime minister, told reporters the judges would be given protection by the army during the reading of the verdict. Some 600 police would also be in place. A small gathering of royalist, anti-Thaksin "yellow shirts" was expected in front of the court. The draft constitution bill, debate on which was blocked by the Constitutional Court in June, would set up an assembly of elected representatives to revise the constitution. If the court now allows the government to press ahead, the bill could be debated in the parliamentary session starting in August. Editing by Alan Raybould and Raju Gopalakrishnan