Thailand’s Constitutional Court has rejected allegations that government plans to amend the constitution are an attempt to overthrow the monarchy.
The court dismissed opposition petitions arguing the changes would undermine Thailand’s revered monarchy.
Lawmakers from the ruling Pheu Thai party see the constitution as undemocratic because it was created after a 2006 army coup.
Security at the court was tight, amid fears of mass demonstrations.
The ruling party could have faced being dissolved by the court if the ruling had gone the other way.
Hundreds of police surrounded the court amid fears that the confrontation could re-ignite Thailand’s bitter political struggle.
Twice in the past five years, the court has disbanded Thailand’s governing party, so supporters of Pheu Thai had already started to gather, fearing the worst, says the BBC’s Jonah Fisher in Bangkok.
The court said that parliament could only only rewrite the constitution on a piecemeal basis, adding that a referendum was needed to decide whether the government could go ahead with the proposed changes wholesale.
Pheu Thai is headed by Thailand’s Prime Minister, Yingluck Shinawatra, sister of deposed former Prime Minister Thaksin Shinawatra. Mr Thaksin was ousted by the military in a September 2006 coup and is now living in self-imposed exile in Dubai.
Rivalry between his supporters and opponents, known as red shirts and yellow shirts, has been a frequent cause of political unrest in the country.
The yellow shirts were behind the huge street protests that led up to the military coup of September 2006 and the ones two years later which led to Mr Thaksin’s allies being forced from power.
In April 2010, the red shirts occupied Bangkok’s historic and commercial districts in an attempt to topple the government. The demonstrations turned violent when the army tried to disperse protesters, with at least 17 civilians and four soldiers killed in clashes.