Move Forward Party MP Rangsiman Rome lodged a petition with the Judicial Commission on Wednesday seeking a probe into the role of several judges regarding the revocation of an arrest warrant against a senator suspected of having links with drug trafficking rings.
He said the petition was related to last month's general debate and it called for an investigation into the role of the Criminal Court chief justice, a Criminal Court deputy chief justice and the judge who presided over the hearing.
Mr Rangsiman said the warrant for the senator was issued in the morning only to be revoked in the afternoon following a recommendation by the Criminal Court chief justice.
Mr Rangsiman alleged the judge was concerned the person was "important" and a police summons must be issued first.
The MFP lawmaker questioned the decision, arguing an arrest warrant can be issued if a suspect faces serious charges related to drug trafficking and money-laundering without having to file for a summons first.
Mr Rangsiman said he wanted assurances that legal procedures were transparent.
"The court at first approved the arrest warrant but revoked it later. Was it because the person is a senator? Under our legal system, senators and the general public are treated equally. I think revocation of the warrant may not be right," he said.
During the general debate in which the government was grilled for its failure to tackle illegal drugs, Mr Rangsiman, without naming names, raised the question of money laundering allegations against a senator with the Thai initial "Or".
After the debate ended, senator Upakit Pachariyangkun filed a defamation lawsuit against Mr Rangsiman, seeking 100 million baht in damages. He also filed a lawsuit against the hosts of a news programme.
