Lawyers for South Korea’s impeached president say he will appear at a hearing in a Seoul court to oppose a formal arrest over last month’s imposition of martial law.

President Yoon Suk Yeol, a former prosecutor, used to put people in jail. Now, after his formal arrest, he himself is in a cell, alone.

Yoon, who was impeached and suspended from office in December, is the first sitting South Korean president to be arrested.

South Korea’s impeached president, Yoon Suk Yeol, was sent to a detention center near Seoul on Wednesday night, after being ...