South Korea’s former president Yoon Suk Yeol has been sentenced to life imprisonment for leading an insurrection, just over a year after he attempted to impose military rule.
His brief declaration of martial law threw South Korea into turmoil, deeply divided the nation, and contributed to a landslide victory for the opposition six months later.
Yoon, 65, had already received a five-year prison sentence for abuse of power and obstructing his own arrest. He is also facing two additional trials. However, the latest ruling concerns the most serious charge — leading an insurrection.
Insurrection
Insurrection refers to the act of rebelling against or attempting to overthrow an established government or state authority, often through violent means.
Under South Korea’s constitution, sitting presidents are immune from criminal prosecution except in cases involving insurrection or treason.
On Thursday, a court in Seoul ruled that Yoon’s actions on 3 December 2024 — including deploying military troops to block the National Assembly and ordering the arrest of politicians — amounted to attempts to undermine the constitution.
“The court finds that the intention was to paralyse the assembly for a considerable period,” presiding judge Ji Gwi-yeon said while convicting Yoon as the “chief insurrectionist”.
Prosecutors had sought the death penalty, describing Yoon as “unrepentant” and arguing that a lesser sentence might fail to deter similar actions in the future.
Yoon previously claimed he declared martial law to defend the country against “anti-state” forces sympathetic to North Korea. However, it later emerged that he was facing declining approval ratings, political scandals, and pressure from an opposition seeking to investigate his wife over corruption allegations.
Even during his trial, Yoon defended the martial law order, describing it as “a measure to protect the freedom and sovereignty of the people and to preserve the nation and its constitution”.
Yoon’s decree and the legal battles that followed prompted large numbers of both supporters and critics to stage protests.
This is not the first time a former South Korean leader has been convicted for involvement in an insurrection.
Chun Doo-hwan, who ruled South Korea as a military dictator in the 1980s, was sentenced to death for leading an insurrection, though the sentence was later commuted to life imprisonment. His successor and ally Roh Tae-woo received a lengthy prison term for his role. Both were eventually pardoned.
Prosecutors argue that Yoon’s 2024 attempt at martial law “tarnished the nation’s dignity far more severely” than the 1979 military coup staged by Chun and Roh.
Law professor Lim Ji-bong told the BBC before the verdict that a life sentence was likely in order to “avoid making Yoon a martyr”. He noted that imposing the death penalty could further polarise the country and intensify unrest.
Even if Yoon had received the death penalty, it would effectively amount to life imprisonment, as South Korea has not carried out an execution since December 1997.
US-based lawyer and Korea specialist Christopher Jumin Lee suggested that Yoon could eventually be pardoned, as Chun and Roh were.
“It’s a customary thing about Korean politics,” Lee said. “Whatever the sentence, it’s just a symbolic acknowledgement of how severe the crime is.”
Obstruction of justice
In January, Yoon was found guilty of obstruction of justice for evading arrest, abuse of power for failing to convene a cabinet meeting before declaring martial law, and falsifying official documents.
Prosecutors accused him of using state institutions “for personal purposes” to conceal misconduct and weaken constitutional checks and balances.
In January last year, around 3,000 police officers were deployed over two attempts before Yoon was finally taken into custody for questioning over the insurrection charge.
Yoon had mobilised security personnel who formed a human barricade inside his residence to block his arrest — an action a special prosecutor described as unprecedented.
Yoon argued that the Corruption Investigation Office lacked jurisdiction to investigate insurrection charges.
Mason Richey, an associate professor at Seoul’s Hankuk University of Foreign Studies, said the chaotic arrest attempts highlighted “apparent lawlessness by Yoon, [his] conservative party, and South Korea’s domestic security institutions”.
“The obstruction of justice trial is a way to ensure accountability for these,” he said.
It ultimately required about 3,000 officers to carry out the arrest in January last year.
Aiding an enemy state
Prosecutors have also alleged that Yoon attempted to provoke North Korea into attacking the South to justify his declaration of martial law.
They cited evidence from the phone of former military intelligence chief Yeo In-hyung suggesting possible provocations, as well as a memo appearing to encourage creating instability or exploiting an emerging situation.
The trial, which began in January, will examine claims that Yoon ordered drone flights into North Korea to incite military conflict, among other allegations.
Yeo and former defence minister Kim Yong-hyun have also been charged in connection with this accusation.
Other charges
Yoon has additionally been accused of perjury during testimony in former prime minister Han Duck-soo’s trial on charges related to aiding the insurrection.
Prosecutors allege that Yoon falsely claimed he had long planned to convene a cabinet meeting before declaring martial law. Investigators say no such plan existed and that the meeting was held only after Han urged him to do so.
Beyond the charges connected to the martial law attempt, Yoon faces other indictments.
He is among 33 individuals charged with allegedly obstructing an investigation into the 2023 death of a young marine officer and aiding a suspect in that case.
He has also been charged with interfering in the 2022 presidential election and making false statements during his campaign.