Real estate tycoon Srettha becomes the fourth Thai premier in 16 years to be removed in verdicts by the same court after its judges ruled 5-4 in favour of dismissing him for failing to perform his duty with integrity.
Srettha's removal after less than a year in power means parliament must convene to choose a new premier, with the prospect of more uncertainty in a country dogged for two decades by coups and court rulings that have brought down multiple governments and political parties.
"The court has found 5-4 that the accused is terminated as prime minister due to his lack of honesty," the judges said on Wednesday, adding his behaviour "grossly breached ethical standards".
The court ruled that Srettha Thavisin's behaviour "grossly breached ethical standards". (EPA PHOTO)
The ruling underlines the central role Thailand's judiciary has played in politics, with the same court last week dissolving the anti-establishment Move Forward Party after ruling its campaign to reform a law against insulting the crown risked undermining the constitutional monarchy.
Move Forward's surviving MPs regrouped on Friday under a new party.
The decision also comes at a tricky time for an economy that Srettha struggled to jump-start, with weak exports and consumer spending, sky-high household debt and more than a million small businesses unable to access loans.
Srettha's Pheu Thai Party and its predecessors have borne the brunt of Thailand's turmoil, with two of its governments removed by coups in a long-running grudge match between the party's founders, the billionaire Shinawatra family, and their rivals in the conservative establishment and royalist military.
"I am saddened to leave as a prime minister who was found to be unethical," Srettha told reporters at Government House.
"I performed my duties with integrity and honesty."
Deputy premier Phumtham Wechayachai is expected to take over as caretaker prime minister.
The ruling could rock a fragile truce between political heavyweight Thaksin Shinawatra and his enemies among the conservative elite and military old guard, which enabled the tycoon's return from 15 years of self-exile in 2023 and ally Srettha to become premier the same day.
Thaksin Shinawatra's daughter Paetongtarn Shinawatra is among the options for Thailand's next PM. (AP PHOTO)
Srettha had maintained his appointment of former Shinawatra lawyer Pichit Chuenban, who was briefly imprisoned for contempt of court in 2008 over an alleged attempt to bribe court staff, was above board.Â
The bribery allegation was never proven and Pichit resigned in May.
According to some political experts, it is likely Pheu Thai would still have the clout to lead the next administration after a period of horse-trading and uncertainty over who will be in charge.
"The coalition remains united," said Olarn Thinbangtieo, deputy dean of Burapha University's Faculty of Political Science and Law.
"There may be some impact on confidence, but that would be in the short term."
The next premier would need to have been nominated a prime ministerial candidate by their parties before the 2023 election, with Thaksin's 37-year-old daughter and party leader Paetongtarn Shinawatra among Pheu Thai's options.
If successful, she would be Thailand's third Shinawatra premier after Thaksin and her aunt, Yingluck Shinawatra.
Other potential candidates include Interior Minister Anutin Charnvirakul, Energy Minister Pirapan Salirathavibhaga and Prawit Wongsuwan, an influential former army chief who was involved in the past two coups.
