Prime Minister Han Duck-soo attends a hearing of his impeachment trial at the Constitutional Court in Seoul, Feb. 19. Joint Press Corps

Prime Minister Han Duck-soo's impeachment verdict could serve as a litmus test for the potential removal of President Yoon Suk Yeol, legal experts said Friday.

The Constitutional Court announced Thursday it will deliver its verdict on whether to uphold Han's impeachment at 10 a.m. Monday. However, the court has not yet disclosed the date for its ruling on the president's impeachment trial for his Dec. 3 martial law declaration.

The ruling on Han's impeachment will come 87 days after the National Assembly passed a motion to oust him for his alleged involvement in Yoon's martial law imposition. His impeachment trial concluded on Feb. 19 after only one hearing.

At the core of Han's impeachment trial are several allegations: his purported involvement in the president's martial law imposition, his refusal to appoint additional justices to the Constitutional Court, his refusal to appoint a permanent special counsel to investigate insurrection charges against Yoon, his failure to promulgate two special counsel bills targeting Yoon and first lady Kim Keon Hee, and his efforts to manage state affairs alongside former ruling People Power Party (PPP) leader Han Dong-hoon.

The prime minister argues that all grounds for his impeachment presented by the National Assembly are invalid, claiming he opposed Yoon's martial law declaration and had no involvement in the mobilization of troops. If the court upholds the impeachment motion, Han will be removed from office. However, if the court rejects it, he will be reinstated as both acting president and prime minister.

Legal experts predict that Han's impeachment will likely be dismissed.

"The charges brought against Han are serious, but not necessarily severe enough to warrant impeachment. It is also clear that Han was not an active proponent of Yoon's martial law declaration," said Cho Jae-hyun, a law professor at Dong-A University.

Pundits believe the verdict on Yoon's impeachment will closely follow Han's case, with the court possibly delivering its decision as early as March 28.

"I think the Constitutional Court is taking much longer than expected to issue its ruling on Yoon's impeachment because justices are unable to reach a consensus. Another possibility might be that they are worried about public backlash in case of dismissing the impeachment motion. Regardless of the result and whether it's a unanimous or a split vote, the court should deliver its ruling as soon as possible," Cho said.

He also warned that justices should be insulated from political pressure in making their decisions. Rep. Lee Jae-myung, leader of the main opposition Democratic Party of Korea (DPK) and a clear favorite to win if a presidential election is called, is scheduled to appear in court on Wednesday to appeal a one-year suspended jail sentence for violating election laws.

Opposition party lawmakers submit a bill to impeach acting President Choi Sang-mok at the National Assembly in Seoul, Friday. Joint Press Corps

Tensions have been rising in recent weeks after the final hearing of Yoon's impeachment on Feb. 25, with both pro- and anti-impeachment groups holding rallies in front of the Constitutional Court and in other parts of Seoul. Some opposition lawmakers have launched hunger strikes calling for Yoon's swift removal, while some Yoon supporters shaved their heads in protest against the impeachment.

Five opposition parties, including the DPK, introduced an impeachment motion against acting President Choi Sang-mok on Friday over his non-appointment of a ninth justice at the Constitutional Court.

Choi appointed two of the three justice nominees recommended by the National Assembly in December, but held off the appointment of opposition-recommended candidate Ma Eun-hyuk, citing a lack of consensus between the PPP and the DPK. In response, National Assembly Speaker Woo Won-shik requested a ruling on the constitutionality of Choi's decision.

In a unanimous ruling on Feb. 27, the Constitutional Court found that Choi's non-appointment of Ma violated the Assembly's right to recommend a justice to the court.

In response to the opposition bloc's move to impeach Choi, the PPP announced plans to file a coercion complaint against DPK leader Lee Jae-myung.