According to prosecutors, Park Sung-Jae held a meeting with officials from the Justice Department after the declaration of martial law, and checked prison capacity in case authorities arrested people critical of the government.
"Due to the defendant's actions, the country almost faced a situation where the fundamental rights of the people and the basic order of liberal democracy could have been violated," the court's president said on Monday.
Former President Yoon Suk-Yeol declared martial law in December 2024. The state of emergency lasted about six hours.
Yoon Suk-Yeol has since been convicted of leading a rebellion and is in custody while he appeals his life sentence.
