South Korea’s impeached President Yoon Suk Yeol appeared in a Seoul court on Thursday for his first trial hearing on charges of insurrection in the country’s first criminal prosecution of an incumbent leader.

Last month prosecutors indicted Yoon after accusing him of leading an insurrection with his short-lived imposition of martial law on December 3.

A justice ministry motorcade took Yoon from the Seoul Detention Center, where he is being held, to the court, outside which were parked lines of police buses to ensure security.

Prosecutors called for swift proceedings considering the gravity of the case, but Yoon’s lawyers said they needed more time to review records.

Yoon had “no intention to paralyse the country,” one of his lawyers told the court, adding that his martial law declaration aimed to tell the public of the “legislative dictatorship of the huge opposition party.”

If convicted, Yoon could face years in prison for his martial law decree, which shocked the country and sought to ban political and parliamentary activity and control the media.

The move unleashed political upheaval in Asia’s fourth-largest economy and a top US ally, with the prime minister also impeached and suspended from power, while top military officials were indicted for their part in the matter.

The court also heard a bid by Yoon’s lawyers to cancel his detention, saying the matter had been investigated in an illegal manner, and that there was no risk of Yoon trying to destroy evidence.

It was unclear when the court would rule on the detention, but a judge set the next hearing of the criminal case for March 24.

After the criminal case, Yoon also attended on Thursday afternoon a parallel impeachment trial by the Constitutional Court that has entered its final phase.

Witnesses testifying to the court included Prime Minister Han Duck-soo, who has also been impeached and awaits the court’s decision on his fate.

“I am deeply burdened by the despair that each and every one of our people felt due to such extreme politics that took place before, during and after emergency martial law,” Han said.

“All procedures dealing with the emergency martial law must be carried out fairly and reasonably … so that there is no further spark of national division.”

The Constitutional Court is reviewing parliament’s impeachment of Yoon on December 14 and will decide whether to remove him from office permanently or reinstate him.

Yoon and his lawyers have argued that he never intended to fully impose martial law but had only meant the measures as a warning to break a political deadlock.

If Yoon is removed, a new presidential election must be held within 60 days.