Yoon Suk Yeol sentenced to life in prison for leading insurrection in South Korea | Yoon Suk Yeol

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

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

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

Yoon maintained his innocence throughout the trial, characterising the investigation as a “political conspiracy”. He said he declared martial law to alert citizens to what he described as an unconstitutional parliamentary dictatorship by the then-opposition Democratic party.

Yoon alleged election fraud without providing evidence and claimed the opposition had paralysed his government through budget cuts and impeachment proceedings.

He argued that he deployed minimal, largely unarmed troops with no intention to suppress parliament. His legal team argued: “There was no intent to disrupt constitutional order, and there was no riot.”

The verdict was announced 14 months after the insurrection, which was the most serious threat to South Korea’s democracy in decades.

The charges stem from events on the night of 3 December 2024, when prosecutors said Yoon attempted to use military force to paralyse the legislature, arrest political opponents and seize control of the national election commission. Yoon claimed he was rooting out “anti-state forces” and alleged election fraud without providing evidence.

Within hours of the declaration, 190 lawmakers broke through military and police cordons to pass an emergency resolution lifting martial law. Parliament impeached Yoon within 11 days, and the constitutional court removed him from office four months later.

Thursday’s verdict follows a series of related rulings that formally established the events of 3 December constituted an insurrection.

In January, the former prime minister Han Duck-soo was given a 23-year prison sentence in a ruling that described the martial law attempt as a “self-coup” by elected power that was more dangerous than traditional uprisings. The sentence far exceeded prosecutors’ 15-year demand, indicating judicial willingness to impose severe penalties.

On 12 February, the former interior minister Lee Sang-min was jailed for seven years for his role in the insurrection, including relaying Yoon’s orders to cut power and water to media outlets.

Legal experts said the rulings created a sentencing environment that made the most severe punishment more likely in Yoon’s case.

The former president Park Geun-hye was initially sentenced to a combined 32 years in prison for corruption and related offences in 2018 before the term was reduced on appeal and later wiped out by a presidential pardon in 2021.

In 1996, military dictators Chun Doo-hwan and Roh Tae-woo received death and 22 and a half-year sentences respectively for their roles in a 1979 coup and subsequent massacre in Gwangju, though those were later reduced on appeal, and both men were eventually pardoned.

Every South Korean president who has served a prison sentence has ultimately been pardoned.