Acting President Han Duck-soo delivers a public address at the Government Complex Seoul, Thursday. Yonhap

The main opposition Democratic Party of Korea (DPK) submitted a motion to impeach acting President Han Duck-soo, Thursday, after he refused to accept the party's demand to immediately appoint three more Constitutional Court justices for President Yoon Suk Yeol's impeachment trial.

The DPK proposed the motion and reported it at a plenary session of the National Assembly, with plans to hold the vote on Friday.

The Constitutional Court, currently operating with only six out of nine justices due to vacancies, normally requires seven judges to review cases. However, an injunction has temporarily waived this requirement, allowing the court to proceed with the impeachment case against President Yoon Suk-yeol, despite being understaffed.

Yet an impeachment decision upheld by only six justices could face legitimacy concerns due to the significance of the issue.

The motion to impeach the acting president came after Han issued an emergency public address to announce he would not appoint the new justices until the ruling and opposition blocs reach an agreement on the matter. The address was made about an hour before the opposition bloc approved their nominations at the plenary session, despite protests from the ruling People Power Party (PPP).

In the address, Han called for the rival parties to reach a bipartisan agreement on the justice appointments.

The opposition has called for the immediate appointment of two justices recommended by the DPK and one by the PPP, so the court can make decisions with a full panel of nine members. However, the PPP claims that the authority to appoint Constitutional Court justices lies with the president, not the acting president.

"Once the ruling and opposition parties reach an agreement and submit their joint proposal on the matter, I will immediately appoint the justices," the acting president said during the address.

Saying that historically, no Constitutional Court justice has ever been appointed without bipartisan agreement, Han argued that an acting president should refrain from exercising significant presidential powers, including appointments at constitutional institutions.

"If such significant presidential powers are to be exercised by the acting president, bipartisan agreement must first be reached. It is the long-standing practice that has remained unbroken throughout the history of the nation's Constitution," Han noted.

However, the DPK quickly moved to seek Han's impeachment, following through on earlier threats to do so if he refused to appoint the justices.

An opposition-led proposal to approve three Constitutional Court justice nominees is put to vote during a plenary session at the National Assembly in Seoul, Thursday. Most members of the ruling People Power Party boycotted the session. Yonhap

While the vote for Han is slated for Friday, the required quorum for the impeachment vote is expected to become another point of political wrangling. The Constitution states that an impeachment motion against the president requires the approval of at least two-thirds of the National Assembly members — 200 out of 300. However, an impeachment motion against a Cabinet minister only requires the approval of a majority, or 151 votes out of 300 lawmakers.

The opposition argues that, since the acting president is the prime minister, the motion should require 151 votes. The ruling PPP, however, argues that since Han is serving as the acting president, the motion should meet the quorum requirement for a presidential impeachment.

If the vote can be held according to the prime minister's standard, the 170-member DPK can pass the motion on its own, but if it follows the president's standard, at least eight defecting votes from the PPP would be needed.

National Assembly Speaker Woo Won-shik looks at the result of a vote to approve three Constitutional Court justice nominees during a plenary session at the National Assembly in Seoul, Thursday. Yonhap

Meanwhile, the opposition bloc also approved the nominations for the three Constitutional Court justice nominees — Ma Eun-hyuk, Jeong Gye-seon, and Cho Han-chang.

Almost all PPP lawmakers boycotted the session, with only three — Reps. Kim Sang-wook, Kim Yea-ji, and Han Zee-a — participating in the vote despite their party's stance to abstain. They criticized their party's decision as "undemocratic and cowardly."