The House of Representatives on Thursday passed an executive decree on the partial transfer of army units, and budget, to a royal security command unit, in the face of strong opposition from the Future Forward Party (FFP).
The House passed the executive decree by 374-70 votes.
The FFP argued that use of an executive decree for a "non-urgent" matter showed a problem of the cabinet misusing its power in violation of the constitution.
The decree provides for the transfer of some of the manpower and budget allocation of the 1st Infantry Regiment of the Ratcha Wallop Royal Guards and the 11th Infantry Regiment of the Ratcha Wallop Royal Guards to the royal security command unit.
The unit is tasked with planning, directing, coordinating and supervising operations which provide security and guard Their Majesties the King and Queen, the heir to the throne, royal family members, royal representatives, people acting at the command of the King, and royal guests.
There were 446 MPs present in the House for the vote on Thursday. The 70 MPs who voted against the decree are members of the 81-strong opposition Future Forward Party. Two MPs abstained — FFP MP for Chiang Mai Srinuan Boonlue and government MP Pol Maj Gen Surin Palare of the Democrat Party.
Three FFP MPs voted for the decree — Chon Buri MP Kawinnart Takee and Chanthaburi MPs Jaruek Sri-on and Pol Lt Col Thanaphat Kittiwongsa.
Before the vote, FFP secretary-general and list-MP Piyabutr Saengkanokkul told the House the executive decree violated Section 172 of the constitution, which says executive decrees should be used for urgent issues. He said the executive decree did not reflect any urgency.
The armed forces were answerable for royal security, it was their main responsibility, Mr Piyabutr said.
He criticised Prime Minister Prayut Chan-o-cha for issuing the executive decree.
"The issuing of this executive decree shows a problem with the cabinet exercising its power, and Prime Minister and Defence Minister Prayut Chan-o-cha is familiar with possessing and exercising special power," Mr Piyabutr said.
"I reserve the right to oppose the executive decree because it does not comply with the constitution. It is not a matter of urgency, or an emergency. This is to show my disapproval of Gen Prayut exercising power exempted by the constitution in a way that will create a habit of ignoring the constitution."
Both Deputy Defence Minister Gen Chaichan Changmongkol and Democrat MP Pirapan Salirathavibhaga told the House that passage of the executive decree was important and urgent.