Lawmakers of the ruling People Power Party protest against National Assembly Speaker Rep. Woo Won-shik after he asked them to end their filibuster during a plenary session at the National Assembly in Seoul, Thursday. Yonhap

The opposition-controlled National Assembly passed a contentious bill, Thursday, mandating a special counsel probe into allegations surrounding the death of a Marine despite fierce protests from the ruling party.

The bill, which was passed with support from 189 lawmakers out of 190 present at a plenary session, aims to initiate an investigation into the government's alleged interference in the military's investigation of Marine Cpl. Chae Su-geun's death, which occurred during a search and rescue operation in a flooded area in July 2023.

Most lawmakers of the ruling People Power Party (PPP) boycotted the vote and walked out of the chamber in protest before voting began while Rep. Ahn Cheol-soo of the PPP voted in favor of the bill.

The main opposition Democratic Party of Korea (DPK) believes that the presidential office may have exerted pressure during the Marine Corps' internal probe.

The passage of this bill underlines the deep divide between the rival parties. The PPP has been staging a filibuster since Wednesday afternoon to block the bill's passage after it was tabled during the Assembly's plenary session. The filibuster ended on Thursday afternoon due to the National Assembly Act, which allows a three-fifths majority to end a filibuster after 24 hours.

The DPK-led bill had initially passed through the previous National Assembly on May 2, but was scrapped in a revote after President Yoon Suk Yeol vetoed it on May 21. The DPK proposed it again after the new National Assembly kicked off in late May. The newly passed bill is a revised version of the original one, with changes to clauses regarding the special investigation committee's composition and method of investigation.

Yoon is expected to exercise his veto for the special counsel probe bill again, which targets the government's alleged interference in the military's investigation into the Marine's death.

The presidential office expressed strong regret over the DPK railroading the bill although it was rejected in a revote after Yoon's veto, calling the move "unconstitutional."

"We deplore the shameful infringement upon the Constitution in the history of our Constitution," a senior presidential official said, requesting anonymity.

If Yoon opposes the special counsel probe bill, conflicts between the rival parties will likely escalate further. The controversial bill continues to be a tremendous burden on Yoon while he is facing increasing impeachment calls on the Assembly's public petition website. Over 1 million users signed an online petition calling for Yoon to be impeached.

The PPP opposes the bill, saying that the police and the Corruption Investigation Office for High-ranking Officials are already investigating the case.

"The Assembly is operating under the DPK's dictatorship. The DPK's addiction to impeachment and legislative monopoly is beyond common sense. Not only has the DPK made the Assembly its playground, but it's not shying away from taking control of the executive branch, judicial branch and media," Rep. Choo Kyung-ho, floor leader of the PPP, said.

When Assembly Speaker Rep. Woo Won-shik tried to end the filibuster at a plenary session, the PPP lawmakers slammed him for not staying "politically neutral" and asked him to step down from the role.

On Thursday morning, DPK floor leader Rep. Park Chan-dae warned Yoon of exercising his veto power following the vote. "If Yoon exercises his veto, he will be put on a path for catastrophe and downfall," Park said during a party meeting.

The 22nd Assembly's official opening ceremony, which was scheduled for Friday, has been abruptly postponed after the PPP said it wouldn't attend the event.