The Supreme Court on Tuesday scheduled the first witness hearing for Aug 25 in a case against 44 former MPs of the now-dissolved Move Forward Party (MFP).
They are accused of serious ethical misconduct for jointly submitting a bill seeking to amend Section 112 of the Criminal Code.
The court also dismissed a separate petition seeking to suspend People's Party (PP) leader Natthaphong Ruengpanyawut from performing his duties.
The now-dissolved MFP has since been reconstituted as the PP.
The Supreme Court held its first hearing on Tuesday after the National Anti-Corruption Commission (NACC) petitioned it to determine whether the former MPs had committed a serious breach of ethical standards.
Of the 44 respondents, 10 are now members of the PP, including its leader, Mr Natthaphong.
The court accepted written objections from all 44 respondents and scheduled an examination of evidence for Aug 4. Both sides were instructed to submit proposed examination procedures and any requests to summon witnesses by July 25.
The first witness hearing is set for Aug 25, with further hearings on Sept 22 and Oct 27. The court plans to hear 17 witnesses and has set a one-year timeframe for the proceedings.
One respondent will act as his own lawyer, while another will conduct his own defence without appointing legal counsel.
After the hearing, former Move Forward deputy leader Pol Maj Gen Supisarn Bhakdinarinath said he had exercised his legal rights in accordance with judicial procedures and had challenged the admissibility of certain evidence in his written submission.
He said the outcome would depend on the court's fairness and added that the former MPs had encouraged one another throughout the process, with some appointing lawyers and others choosing to represent themselves.
NACC assistant secretary-general Phattanaphong Chanphetphoon said the commission's submission detailed the conduct of each respondent individually.
Whether the cases would be heard separately or together would be decided by the court. The commission has proposed 17 witnesses, including case officers and former Move Forward MPs who previously gave statements, although the final decision rests with the court.
The court also rejected a petition by Nopparut Worachitwuttikun, a former leader of the White Dove 2006 group, seeking an order suspending Mr Natthaphong over remarks concerning the participation of some privy councillors in a meeting held by the Department of Disaster Prevention and Mitigation.
