“It’s against the Constitution to vote for another person in Parliament,” said Senator Rosana Tositrakul, who represents Bangkok.
She caught one of the MPs putting an extra card into a voting slot behind his seat, she told a press conference at Parliament House.
She showed her iPad with an incriminating photo of the MP, taken from behind.
The chamber was almost deserted during the deliberations but MPs often rushed back to vote, she said.
The same photo was also on her Facebook page, she said.
Senator Somchai Sawaengkarn also said more security cameras should be installed to record any lawmaker voting for others by using their cards.
“It’s against the law and the Constitution to vote for others,” he said.
Some senators were collecting information about the incident to lodge a complaint with the Constitution Court, he said.
Democrat MP Boonyod Sukthinthai said he would raise the matter at today’s meeting of the House committee on parliamentary affairs.
The act was against the floor regulations and code of conduct, he said.
Rak Thailand Party leader Chuwit Kamolvisit, at a separate press conference, showed footage of MPs reaching out to panels in front of other seats to vote.
The MP also displayed a “button” camera he said had been hidden in his suit jacket while he was filming the acts.
Since MPs voted for others, the voting in support of the government’s amendment bill might be regarded as unlawful, so he would petition the Constitution Court to rule on this matter.
Prompong Nopparit, spokesman for the ruling Pheu Thai Party, said the new scandal might be aimed at distracting the public from an earlier one involving Democrat MP Nutt Bantadtan, who was photographed looking at an image of a scantily-clad woman on his cellphone.
Nutt defended himself by saying he was just checking his Facebook messages when this picture came up.