The NACC unanimously decided against Mr Somsak who was charged with violating the Constitution for his involvement in the attempt to amend a provision in the Constitution.
NACC members Prasart Pongsivapai and Vicha Mahakhun, the latter the agency's official spokesman, together told a press conference that the NACC learned that Mr Somsak submitted a constitutional amendment draft to Parliament for consideration which was different from the original draft, without MP and senatorial endorsements as required by the Constitution.
Mr Vicha said that Mr Somsak was also faulted for depriving several MPs of their right to debate the amendments draft.
The NACC ruled Mr Somsak’s acts were in violation of the Constitution and that it would recommend that he be impeached by the Senate.
The decision will be sent to the Senate to proceed with the impeachment.
On March 20, Senate speaker Nikom Wairatpanich was also indicted by the NACC for exercising his power in violation of the Constitution during a parliamentary debate on a Constitution amendment concerning the composition of the Senate.
He is facing impeachment by the Senate.
As for caretaker Prime Minister Yingluck Shinawatra's request that NACC question addition of 11 witnesses to defend allegations that she was negligent in not preventing graft in the loss-making project, Mr Vicha said that NACC has allowed three of the 11 defence witnesses to testify
Ms Yingluck was charged with dereliction of duty in connection with the government's rice-pledging scheme.
The three witnesses were caretaker Finance Minister Kittiratt Na-Ranong, caretaker Commerce Minister Niwatthamrong Boonsongpaisan and caretaker Deputy Commerce Minister Yanyong Phuangrach.