Holiday Post: The legal team for South Korea's impeached president argued on Thursday that Yoon Suk Yeol did not commit insurrection during his dramatic imposition of martial law this month.

Yoon was stripped of his duties by parliament in an impeachment vote at the weekend after his short-lived declaration of martial law on December 3, which plunged South Korea into its worst political turmoil in decades.

The Constitutional Court began proceedings against Yoon on Monday and has about six months to decide whether to uphold his impeachment.

Yoon is also being investigated by a joint team of police, defence ministry and anti-corruption investigators.

"Where in the world does a leader declare an insurrection during a live press conference?" Seok Dong-hyeon, a spokesman for Yoon's legal team, told a media briefing in Seoul.

Yoon made his martial law declaration in a live television announcement, although it was voted down by lawmakers several hours later.

"Where can you find an insurrection that ends within two or three hours because the National Assembly told them to stop martial law?" said Seok.

South Korean lawmakers forced their way into parliament through lines of soldiers to vote down Yoon's martial law declaration.

Vast protests against the ousted leader, with smaller rallies supporting him, have since rocked the South Korean capital.

Yoon and some of his inner circle face possible life imprisonment, or even the death penalty, if found guilty. He remains under a travel ban.

Seok said Yoon remained "clear and confident" about fighting his case in court.

Yoon failed to appear before South Korea's corruption watchdog on Wednesday after being summoned for questioning, the Corruption Investigation Office said.

The Constitutional Court also ordered Yoon on Wednesday to submit his martial law decree, as well as records of cabinet meetings he held immediately before and after the announcement.

It has set a preliminary hearing for December 27, although Yoon is not required to attend.