Former House speaker Somsak Kiatsuranon Thursday gave statements in his defence before an inquiry committee set up by the National Legislative Assembly (NLA) in parliament.
It was the first time he had appeared in person to defend himself in impeachment proceedings launched against him by the NLA. He did not attend the first NLA hearing on the impeachment motion last Thursday.
The NLA has set Jan 23 as the date for voting on the impeachment cases against former prime minister Yingluck Shinawatra, Mr Somsak and ex-Senate speaker Nikhom Wairatpanich.
Separate votes will be taken on the impeachment motions against the three.
Ms Yingluck faces impeachment for alleged dereliction of duty in the rice-pledging scheme.
The National Anti-Corruption Commission (NACC) petitioned the NLA to impeach Mr Somsak and Mr Nikhom over their role in chairing a joint House-Senate debate on a charter amendment bill to make the Senate a fully-elected chamber.
The NACC accuses the pair of malfeasance in office, abuse of power and gross violation of ethical conduct in accordance with sections 270 and 291 of the 2007 constitution.
The charges followed a petition filed by former lawmakers seeking the impeachment of the pair, arguing they illegally exercised their power by cutting short a parliamentary debate.
The NACC said Mr Somsak endorsed a motion on March 27, 2013 to debate a charter amendment that would make the Senate fully elected. But the bill Mr Somsak introduced was different from the one proposed by Pheu Thai MP Udomdej Rattanasathian and endorsed by Mr Somsak on March 20.
Mr Somsak's version included changes that would have allowed the elected senators to serve unlimited consecutive terms. The NACC said the principles of the new document were not consistent with those of the original.
During the NLA meeting yesterday, the NLA questioned Mr Somsak, Mr Nikhom and NACC member Vicha Mahakhun.
Mr Somsak denied the NACC's claims regarding alleged falsification of the bill.
He said that legislative bills usually must be sent to the Bureau of Parliamentary Proceedings for checking first before they are submitted to him. But the version of the bill submitted by Mr Udomdej was not put on the parliamentary agenda because he asked it back to make revisions.
After changes were made to the bill, Mr Udomdej resubmitted the document to him, so he put it on the parliamentary agenda, Mr Somsak said.
He also said the director of the Bureau of Parliamentary Proceedings had confirmed there was nothing wrong with the bill in question.
During all three readings of the bill, no legislators questioned its authenticity, Mr Somsak added.
He also said he did not attend the previous NLA hearing to make his opening statement in his impeachment case because he chose to write to defend himself.
He appeared in person yesterday because he needed to clear up confusion and misunderstanding stemming from the accusations, he said.
Mr Nikhom yesterday also testified before the NLA inquiry panel. He denied accusations that he tried to close the debate early, saying he followed parliamentary session proceedings.