A South Korean court on Thursday sentenced former president Yoon Suk Yeol to life imprisonment with labour over his failed declaration of martial law in December 2024, after finding him guilty of leading an insurrection. He becomes the first elected head of state in the country’s democratic era to receive the maximum custodial sentence.

Under South Korean law, the offence of leading an insurrection carries three possible penalties: death, life imprisonment with labour, or life imprisonment without labour.

Prosecutors had sought the death penalty, arguing that Yoon was responsible for a “grave destruction of constitutional order” by mobilising troops to surround parliament and attempting to arrest political opponents during the six-hour crisis.

Yoon denied any wrongdoing throughout the trial, describing the investigation as a “political conspiracy”.

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Yoon abruptly declared martial law in a televised address in December 2024, saying drastic measures were needed to root out "anti-state forces".

Presiding judge Ji Gwi-yeon said Yoon dispatched troops to the assembly building in an effort to silence his political opponents.

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"The Court finds that the intention was to paralyse the assembly for a considerable period," Ji told Seoul Central District Court.

"The declaration of martial law resulted in enormous social costs, and it is difficult to find any indication that the defendant has expressed remorse for that," the judge said.

"We sentence Yoon to life imprisonment."