On Tuesday, the prosecutor submitted the names of 17 witnesses to the Supreme Court, including officials from parliament and the NACC, with the first expected to take the stand on Aug 25.
None of the MPs on trial were in court, according to an AFP reporter.
The next two hearings were set in September and October.
The accused were previously members of the Move Forward party, which had proposed to amend the lese-majeste law.
Thailand’s constitutional court dissolved Move Forward in 2024, ruling that its royal reform pledge amounted to an attempt to overthrow the constitutional monarchy.
Most of its members formed a new party, the People’s Party, under which the 10 MPs currently on trial were re-elected in February.
Natthaphong told a news conference in April after the Supreme Court accepted the case that the reform effort was “never intended to undermine the democratic system under the monarchy”.
“Our objective goes beyond political careers – it is about ensuring equality for the people,” he said.
“We will contest this case in the Supreme Court to defend the rights of MPs within a democratic parliamentary system and to ensure that Thailand’s democracy genuinely serves its people.”