This is also his first public appearance since his arrest in July.
The former president was escorted from detention to a court in central Seoul (Korea) to attend a hearing at 10:15 a.m. (local time). The trial will also be broadcast online.
Mr. Yoon appeared in court in a dark blue suit, wearing a prisoners' card numbered 3617, appearing tired, his gray hair became significantly thinner and thinner than when he was arrested.
Standing in front of the horse's den, he answered the personal check by stating his date of birth and address, then refused to be tried by the jury.
Yoon, who was indicted for rebellion in December 2024, is now facing a trial for several other crimes, including violating the rights of cabinet members, editing martial law declarations and obstructing detention by investigators in January 2025.

He also faced charges of ordering the dilation of call records and spreading false information.
During the hearing, Yoon's lawyers denied the allegations, saying he had only declared martial law in an emergency and had lifted it after the National Assembly voted to cancel it.
They also accused special prosecutor Cho Eun-suk of prosecuting Mr. Yoon for political reasons rather than on legal grounds.
Meanwhile, Mr. Yoon denied the allegations related to the alleged claim as fake, saying that the document was drafted by former presidential secretary Kang Eui-gu after the martial law decree was overturned, in order to legalize his actions but was not eventually published.
Mr. Yoon said that he had scolded Mr. Kang, but Mr. Kang still said he would keep the draft.