• Former South Korean president Yoon Suk Yeol faces insurrection charges.
• Yoon argues his martial law declaration was not a coup d'état.
• The trial includes testimonies from military officers regarding the martial law incident.
• If convicted, Yoon could face life imprisonment or even the death penalty.
• A snap election is scheduled for June 3 to elect his successor.

South Korea's former president Yoon Suk Yeol appeared in court on Monday as his criminal trial commenced, facing charges of insurrection related to his controversial declaration of martial law late last year. Lawmakers impeached Yoon and he was stripped of office earlier this month due to his actions, which included deploying armed soldiers to parliament in an attempt to suppress political dissent, a move that triggered widespread protests and political turmoil, according to Channel News Asia.

During the trial at Seoul Central District Court, Yoon vehemently denied the charges, characterizing his martial law declaration as “not a coup d’etat.” He claimed it was a necessary measure to alert the public about the opposition's attempts to obstruct governmental processes by impeaching over 20 officials, as reported by Reuters.

Prosecutors initiated their case by asserting that Yoon’s martial law was illegally declared and aimed at paralyzing state institutions such as parliament. They maintained that the declaration rendered constitutional institutions incapable of exercising their authority, thus straying into insurrection territory, according to Al Jazeera.

The declaration, which cited a need to combat “anti-state” forces, lasted only six hours, as lawmakers used barricades to prevent military personnel from entering the National Assembly to enforce Yoon's order. Yoon has argued that the martial law was a "peaceful ‘message martial law’” to the nation and had planned for it to end swiftly, an assertion met with skepticism from observers watching the unfolding events, according to South China Morning Post.

The trial is expected to be protracted, with legal experts estimating a verdict may not arrive until August. The prosecution's case includes extensive evidence and numerous witnesses, further complicating the proceedings, as detailed by Channel News Asia.

Should Yoon be found guilty, he risks becoming the third South Korean president convicted of insurrection, potentially facing severe penalties including life imprisonment or the death penalty, though capital punishment has been effectively suspended in South Korea since 1997, according to Reuters.