SEOUL (Reuters) – Yoon Suk Yeol, the impeached president of South Korea, plans to attend a court hearing on Saturday to fight a request by investigators to extend his prison term on sedition charges, the his lawyer said.

Yoon on Wednesday became the country’s first sitting president to be arrested, in a criminal investigation related to his brief declaration of martial law on December 3.

Investigators requested a detention warrant on Friday to extend their custody of Yoon up to 20 days. He has refused to talk to investigators and has been held at the Seoul Detention Center since his arrest.

Police were seen breaking up a crowd of Yoon’s supporters blocking the gate of the Seoul Western District Court, where the hearing is expected to begin at 2 pm (0500 GMT). The decision is expected on Saturday or Sunday.

“He decided to attend … to restore his honor by directly explaining the legitimacy of the emergency martial law and that the insurrection was not founded,” Yoon’s lawyer, Yoon Kab-keun, said in a statement.

The insurrection, the crime charged against Yoon by the Corruption Investigation Office for High-ranking Officials, is one of several for which the incumbent South Korean president has no immunity.

Detention warrant hearings usually last about two hours in South Korea but can last eight to 10 hours if arguments get heated.