The ruling Pheu Thai Party and its patriarch, Thaksin Shinawatra, have been hit with a new legal challenge in the form of a petition filed with the Constitutional Court for alleged treason - similar to one that brought down the Move Forward Party (MFP).

The petition, accusing the ruling party and former Prime Minister Thaksin Shinawatra of treason, was submitted to the Constitutional Court on Thursday (10 October) by conservative lawyer Theerayut Suwankesorn, who previously filed a similar petition against the MFP which led to its dissolution.

The lawyer accuses the ruling party and Thaksin of attempting to undermine the democratic regime with the King as head of state, and asks the Court to order the accused to cease any activities that involve exercising rights and freedom in ways that could lead to the overthrow of the regime.

Paiboon Nititawan, opposition Palang Pracharath Party (PPRP) Secretary-General, previously told the press that a petition would be filed on 10 October, claiming it could mark the beginning of the end for the government. On Thursday, he confirmed to the press that he was referring to Theerayut’s petition. Paiboon denied speculation that Theerayut was acting on an “order” to target the ruling party and Thaksin. Theerayut said he alone decided to submit the petition, insisting that he merely consulted Paiboon on certain points and he had never met Gen Prawit Wongsuwan, the PPRP leader.

However, many speculate that Gen Prawit is behind this move, seeing it as a 79-year-old man’s efforts to take revenge after his dream of becoming prime minister was shattered and his party was kicked out of the government coalition.

The 65-page petition, along with 5,000 pages of additional documents brought to the Court on a trolley, accuses the party and Thaksin of treason in six instances, most of which involve Thaksin’s influence over the party.

Thaksin, who was granted a royal pardon reducing his prison sentence from eight years to one year, spent his entire time in detention on the VIP floor of the Police Hospital and did not spend a single night behind bars, despite reports of improvement in his health. He is accused of failing to comply with the royal pardon.

It is also alleged that he dominated the ruling Pheu Thai Party during the dispute between Thailand and Cambodia in 2001 concerning overlapping maritime claims, influencing the government to favour then-Cambodian leader Hun Sen and allowing Cambodia to infringe on Thailand’s maritime sovereignty. In 2001, Thaksin was Prime Minister and reader of ruling Thai Rak Thai Party which became Pheu Thai.

This controversy stems from the signing of the so-called MOU 44, a 2001 Memorandum of Understanding on joint development of areas claimed by both Cambodia and Thailand. The legality of this MOU was challenged in April by Paiboon but his petition was rejected by the Constitutional Court on 4 September.

Thaksin is also accused of instructing the party to collaborate with the People’s Party on amending the Constitution for his own benefit. The People’s Party consists of former MPs from the MFP which was dissolved by the Court after a treason charge brought by Theerayut.

Thaksin allegedly played a key role in calling a meeting of high-ranking members of coalition parties, including the PPRP, at the Shinawatra’s Chan Song La residence to discuss the nomination of a new PM following the disqualification of the former PM Srettha Thavisin,

Theerayut’s petition also accuses Thaksin of directing Pheu Thai to oust the PPRP from the coalition government, and of pushing Pheu Thai to adopt the policies he outlined on 22 August at a Vision for Thailand event organised by Nation Group for the official policy statement which was presented to parliament by the new administration on 12 September.

Theerayut is a controversial figure. He became known for representing Suwit Thongprasert, a leader of the yellow-shirt People’s Democratic Reform Committee when he was an ultra-royalist monk known as Buddha Issara. Suwit was arrested in a pre-dawn raid in May 2018 and put on trial and convicted in September that year for detaining and torturing 2 police officers in the 2014 PDRC occupation of the Government Complex.

Theerayut also represented former PPRP MP Pareena Kraikupt who was stripped of her MP status, banned from politics for life and ordered to pay the costs of a by-election to choose her successor when she was proved to be the owner of a chicken farm which was largely on public land. Theerayut has also pursued some high profile royal defamation charges, including against Thanathorn Juangroongruangkit, Piyabutr Saengkanokkul and Pannikar Wanich, leaders of the Progressive Movement and former executives of the MFP.

This petition is the most serious challenge yet among those filed against the ruling party, most of which have sought to dissolve the party and disqualify PM Paetongtarn Shinawatra.