The opposition-led National Assembly on Thursday passed a contentious bill mandating a special counsel investigation into the Yoon Suk Yeol administration and the military’s response to a young Marine’s death last year.

Of the total 190 lawmakers that participated in the vote, 189 voted in favor of the bill while one was against it. All ruling People Power Party, except two, boycotted and left the premises before plenary voting took place.

The contentious bill, which calls for the formation of a special counsel to probe allegations that ranking Defense Ministry officials and the presidential office interfered in an internal military investigation into the death of Cpl. Chae Su-geun, was tabled the previous day. Chae, 20, was killed after being swept away by a torrent during a search and rescue mission for victims of heavy downpours in July last year.

The opposition-led Assembly’s move comes after at least three-fifths of the entire 300 parliament members, or more than 180 lawmakers, voted in favor to end the ruling party’s filibuster. The People Power Party’s filibuster had kicked off at around 3:40 p.m. on Wednesday and went for over 24 hours until 4:10 p.m. on Thursday.

Following the passage of the bill, the office of Assembly Speaker Woo Won-shik announced that the opening ceremony for the 22nd parliament, which was initially scheduled for Friday, has been delayed indefinitely.

Prior to Woo’s announcement, People Power Party Floor Leader Choo Kyung-ho, in protest of the main opposition’s unilateral move, declared that the party would boycott the opening ceremony. He added that he plans to request President Yoon, who was to be the keynote speaker at the event, follow their move and refrain from attending the ceremony as well.

During Thursday's plenary session, ruling party lawmakers verbally protested in front of Woo, who presided over the meeting and officially ruled for the end to the filibuster. Under the National Assembly Act, a filibuster can be stopped after 24 hours if at least three-fifths of the full 300 National Assembly members vote to end it. Most People Power Party lawmakers left the premises in protest before voting took place.

The special counsel bill was previously vetoed by Yoon on May 21 after the Democratic Party had passed the bill in the assembly's plenary session on May 2, when the ruling People Power Party's lawmakers had also walked out in protest. The main opposition party reintroduced the bill after the start of the 22nd Assembly session, which kicked off in late May.