BLOOMBERG BANGKOK THAILAND’S political calm hangs in the balance as Prime Minister Yingluck Shinawatra’s ruling party decides whether to defy the nation’s highest court and proceed with an overhaul of a military-influenced constitution.

The Constitutional Court on July 13 called for a referendum before rewriting the charter ratified after a 2006 coup that ousted former leader Thaksin Shinawatra, Yingluck’s brother.

Lawmakers “must take responsibility for their next move” if they proceed with a vote to redraft the constitution, court spokesman Pimon Thammaphitakphong told reporters.

Moving forward without a nationwide vote could “invite more explosive protests from the other side,” Somjai Phagaphasvivat, a political science lecturer at Thammasat University in Bangkok, said by phone.

“Tensions remain high and this will be the situation for months and years to come.” The battle over changing the constitution threatens political stability in Southeast Asia’s second-biggest economy, where street protests since 2006 have killed more than 100 people and led to takeovers of the airports and central business district.

Thaksin’s allies want to reduce the power of appointed bodies they say are undermining elected governments to serve the interest of royalists who backed the coup.

While the eight judges ruled unanimously that a proposal to create a 99-member assembly to rewrite the constitution didn’t breach Article 68, which restricts attempts “to overthrow the democratic regime of government with the King as Head of State,” they said a complete overhaul would require the consent of Thailand’s 67 million people.

The 2007 constitution “came from a referendum,” Judge Nurak Mapraneet said in the ruling. “So the public should hold another referendum to decide whether they want a new draft. If the parliament wants to amend it, it can do by each article.” The referendum requirement appears nowhere in Article 291 of the current charter, which grants parliament the right to change the constitution. Yingluck’s party had proposed changing that article to allow for a complete constitution rewrite that would need to be approved in a referendum after it was drafted.

The court’s insistence that a nationwide vote is required before rewriting the charter amounts to a threat against the government and parliament because the judiciary is asserting powers that aren’t granted in the constitution, according to Kanin Boonsuwan, a law lecturer at Chulalongkorn University who submitted testimony in favour of the amendment.

“If the government and parliament yield to this threat, it means this country is not democratic,” Kanin said.

“Next time there is no need to have an election. Just let the court be the ruling party.” The court’s determination that it has the authority to accept petitions directly from the public instead of solely from the Attorney-General, as occurred in this case, also represents an expansion of the court’s powers, Kanin said.

Prosecutors declined to forward the petitions to the Constitutional Court, saying last month that the amendment process is valid. A committee formed by the previous administration warned the court last month to undertake a “strict interpretation” of the law to maintain public confidence in the judiciary and help prevent violence.

Yingluck campaigned on changing the constitution to make leaders more accountable to the public before her party’s majority win in elections a year ago and included plans for a drafting assembly in a policy statement. Deputy Prime Minister Chalerm Yoobamrung called the ruling “fair” and said Yingluck would decide how to proceed with changing the constitution.