The flag of the Constitutional Court flutters at the court in central Seoul, Sunday, ahead of its rulings on high-profile cases this week. Yonhap

The judiciary is poised to deliver rulings on at least two high-profile cases this week, which are expected to reshape the nation's political landscape.

The political aftermath of the court decisions could be even larger with the possibility for yet another, which, if taking place this week, will be the most important ruling — that for President Yoon Suk Yeol's impeachment over his Dec. 3 martial law declaration.

On Monday, the Constitutional Court will render a verdict on Prime Minister Han Duck-soo, after 192 lawmakers at the National Assembly voted to impeach him on Dec. 27.

The Assembly passed the impeachment motion after accusing him of rebellion by conniving with Yoon to declare martial law on Dec. 3 and of refusing to appoint three Assembly-selected candidates for the Constitutional Court bench, among other charges.

His alleged cooperation in imposing military martial law is intertwined with the impeachment trial for Yoon, the final decision-maker. The justices' views on the legitimacy of that act could be expressed in their ruling on Han, who allegedly tried to prevent the move in a Cabinet meeting before its enforcement.

What triggered the main opposition Democratic Party of Korea (DPK) to push for Han's impeachment was his decision to "delay" the appointments of the three justice candidates. The then-acting president said he had to, because the liberal party had picked two of them without agreement from the ruling People Power Party, as it would be a breach of past practices.

Another issue of great interest and importance is whether it was legal to impeach Han in the first place, with fewer than 200 votes — the number required to impeach a president — as he was serving as acting president, not just a Cabinet member who can be impeached with a minimum 151 votes.

If Han is reinstated, questions are expected to rise over the legitimacy of two Constitutional Court justices — Chung Kye-sun and Cho Han-chang — appointed by Han's successor, Finance Minister Choi Sang-mok. If Han's removal from office was found to be unlawful, conservative politicians and their supporters are almost certainly expected to challenge the validity of the decision to appoint them in his absence.

Rep. Lee Jae-myung, front row right, chairman of the opposition Democratic Party of Korea, calls for the swift ousting of President Yoon Suk Yeol with other party members during a rally in Seoul, Saturday. Yonhap

On Wednesday, the Seoul High Court will rule on Rep. Lee Jae-myung, chief of the DPK, who will face his biggest legal challenge yet.

A lower court found him guilty on Nov. 15 of violating the Election Law by making false claims during an Assembly audit in 2021 while running as a presidential candidate about a land development project in Seongnam, Gyeonggi Province, while he was the city's mayor.

The court at the time gave him a one-year prison term suspended for two years, which would strip him of his Assembly seat and his eligibility to run in any elections for the next five years.

If the appellate court upholds the lower court's ruling, Lee will likely face a more serious obstacle to his leadership as well as his potential candidacy in the next presidential election.

Although he will appeal to the Supreme Court, which, by law, has three months to finalize the case, a second guilty decision will deal a serious blow to his status as the most powerful liberal presidential candidate.

But if Lee is found not guilty, his grip on the party will be tightened further and, if Yoon is ousted, he would almost certainly become its presidential candidate in a snap election, despite many other criminal charges facing him.

Regarding Yoon's impeachment case, the Constitutional Court has not announced a date for its verdict. This defies predictions by many political observers, who expected the court to make its verdict in the middle of March.

Given that in the past, the court informed the president or other high-ranking government officials in question of such schedule two or three days prior to its decisions, there is a possibility for the court to announce the date early this week and deliver its verdict on Thursday or Friday at the earliest.

Even if the ruling on Yoon is not made this week, his trial is widely expected to be finalized before April 18 when two of its justices retire.