The Seoul Central District Court found Yoon guilty of mobilising the presidential security service to block an arrest warrant and for failing to follow the legal process required for declaring martial law, which must be discussed in a formal cabinet meeting.
“The defendant abused his enormous influence as president to prevent the execution of legitimate warrants through officials loyal to him, effectively privatising state resources for personal safety and gain,” said the lead judge on the three-justice panel.
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Yoon, 65, showed no reaction as the sentence was announced in a courtroom packed with supporters. Speaking outside the court, his lawyer Yoo Jung-hwa said the former president would appeal, calling the ruling politicised.
Prosecutors have separately sought the death penalty for Yoon for masterminding an insurrection by attempting to suspend parliament and impose military rule without justification.
Yoon was arrested in January after barricading himself inside his residence and ordering security personnel to block investigators, an unprecedented arrest of a sitting South Korean president. Parliament swiftly overturned his martial law decree and the Constitutional Court removed him from office in April 2025, citing violations of his duties.
While the attempted martial law lasted only about six hours, it caused widespread concern across the country, prompting Parliament to swiftly overturn Yoon’s decree and leading to his eventual impeachment by the Constitutional Court in April 2025.
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Security forces were mobilised to enforce the reversal, and Yoon’s actions triggered investigations into the misuse of presidential authority. Analysts noted that Yoon’s bid to retain power, even briefly, challenged the democratic institutions that had long defined South Korea’s governance, and set the stage for one of the most high-profile trials in the nation’s recent history.
Although the martial law bid lasted only six hours, it sent shockwaves through the country, a key US ally and one of Asia’s most resilient democracies. Yoon joins a list of South Korean leaders who have faced conviction, including former general Chun Doo-hwan, who was sentenced to death in 1996 for the 1980 Gwangju crackdown but later pardoned after two years.