The Constitutional Court agreed on Wednesday to give caretaker Prime Minister Yingluck Shinawatra another 15 days to prepare her defence, but rejected her plea for additional witnesses to defend her over the removal of Thawil Pliensri as National Security Council (NSC) chief.
The deadline for her to submit evidence has been extended to May 2 from April 18.
The court also set May 6 as the date to hear four witnesses -- appointed senator Paiboon Nittitawan, the caretaker prime minister, Wichean Potephosree, and Mr Thawil.
It rejected Ms Yingluck's request that former deputy prime minister Pol Gen Kowit Wattana, caretaker Labour Minister Chalerm Yubamrung and former deputy police chief Pol Gen Achirawit Suphanphesat also be allowed to give testimony in her defence in court.
Ms Yingluck was not at the court on Wednesday, and was represented by her lawyer.
The case was filed by 28 senators led by Mr Paiboon. They asked the court to decide the prime ministerial status of Ms Yingluck after the Supreme Administrative Court ruled her decision to transfer Mr Thawil in 2011 had been unlawful and unfair because she had not given appropriate reasons for Mr Thawil's transfer.
Pheu Thai legal expert Pongthep Thepkanchana on Friday reiterated his belief the prime minister did have authority to transfer Mr Thawil to tothe post of PM's adviser.
Wirat Kalayasiri, chief legal expert of the Democrat Party, argued that Pheu Thai missed the point.
''The prime minister has authority to transfer officials. Nobody argues on that,'' Mr Wirat told FM101 radio station. ''The bottom line in this case is the transfer was to serve the interests of Ms Yingluck, Pheu Thai and the Shinawatra family.''
''Yingluck cannot escape this,'' he added.
Mr Thawil was replaced by Pol Gen Wichean, who was moved from the post of national police chief. Then Pol Gen Priewpan Damapong was promoted from a deputy police commander to succeed Pol Gen Wichean.
Pol Gen Priewpan is the brother-in-law of Ms Yingluck. He is an elder brother of Khunying Potjaman na Pombejra, former wife of Thaksin.
It is possible Ms Yingluck and her cabinet could be removed from even caretaker status, leaving open an opportunity for a neutral prime minister to step in.
Both pro- and anti-government protesters are closely watching the developments in this case. The anti-government group has made no secret of their wish to seize ruling power in the event Ms Yingluck is deposed, while pro-government groups have vowed to prevent it.