South Korean President Yoon Suk Yeol’s political gamble to declare martial law in December, which resulted in his impeachment by the National Assembly, has ended with his dramatic ouster from power less than three years after he took office.

Following a trial in Korea’s Constitutional Court, eight judges deliberated on whether to uphold Yoon’s impeachment or restore his presidential powers. On April 4, they delivered a verdict that his short-lived martial law imposition violated the constitution, resulting in Yoon’s removal from power.

South Koreans will now vote in national elections to determine their next leader. Here’s what to know.

Why was Yoon impeached?

Yoon, who had been president since 2022, declared martial law on Dec. 3, 2024, saying in a nationally televised address that he meant to protect the country from “anti-state forces” and people who sympathized with North Korea. His abrupt decree followed several defeats for his minority government in parliament, including the forced downsizing of plans for the national budget by the opposition bloc led by the Democratic Party. It was the first time a leader had tried to enforce military rule since the launch of full democracy in the nation about 40 years ago — and it backfired spectacularly.

Yoon’s martial law was quickly rejected by all 190 lawmakers who convened for an emergency meeting of the National Assembly. He subsequently lifted the decree some six hours after issuing it. Yoon was impeached on Dec. 14 and summoned for questioning by the Corruption Investigation Office several times, ignoring the summons in each case. An arrest warrant was issued on Dec. 31 and there followed two weeks of uncertainty as authorities sought to apprehend him, prompting a standoff between his security detail and police. In January, the 64-year-old was arrested in a dawn raid on the presidential palace. He was taken into custody and later indicted on criminal charges of leading an insurrection.

Law enforcement authorities inside the compound of South Korean President Yoon Suk Yeol’s residence in Seoul on Jan. 15, 2025, the day Yoon was arrested.Photographer: SeongJoon Cho/Bloomberg

How do the criminal charges differ from the impeachment?

While both relate to his brief declaration of martial law, the impeachment trial was more of a political process to strip Yoon of his presidential powers. A separate criminal case in Seoul Central District Court is underway against Yoon. The charge is insurrection, which according to the country’s law is any attempt to overthrow government organs or subvert the constitution. Prosecutors have prepared 70,000 pages of evidence to support their case. Yoon, who was released from detention in March after successfully challenging the arrest’s validity, is South Korea’s first sitting president to stand trial in a criminal case. If convicted he could face life in prison or even the death penalty. The criminal case against him, however, may take years to resolve.

Who will lead South Korea?

Under the law, South Korea has to hold a presidential election within 60 days following the removal of a president. Political parties will hold primaries in coming weeks to pick a nominee. Lee Jae-myung, head of the main opposition Democratic Party, is considered a top contender from the liberal camp, while Yoon’s People Power Party has yet to put forth a candidate.

Lee is favorite to become president. His party has been looking to increase taxes on wealthy individuals and the chaebol conglomerates that dominate the country’s corporate landscape. Lee touts a more conciliatory approach to relations with North Korea than his political opponents, a stance that might align with Donald Trump if the US leader seeks to revive diplomacy with North Korean leader Kim Jong Un.

His conservative rivals include Seoul Mayor Oh Se-hoon and former PPP leader Han Dong-hoon. Both Oh and Han opposed Yoon’s martial law. Oh touts easing regulations on property redevelopment and supports South Korea’s own nuclear armament.

Whoever wins the election will take power immediately, without the usual transition period, for a single five-year term. Until then, the nation’s Prime Minister Han Duck-Soo will remain as interim leader.

What’s at stake?

The new president will take over the running of a sharply polarized nation that plays a critical role in global tech supply chains and the regional security power balance. The winner will need to quickly fill the leadership vacuum that has left the nation vulnerable as Trump embarked on a wave of protectionist trade policies and North Korea deepened its relations with Russia.

The new president will want to show that he or she can negotiate with the US and limit the impact of tariffs on Asia’s fourth-largest economy and ensure that Washington remains fully committed to its ally on the divided peninsular. The new leader will want to bring the nation together and push ahead with policy that restores momentum in the economy without getting bogged down in the parliamentary stalemate that contributed to Yoon’s gamble.

An exceptional leader would restore stability and growth to the economy and demonstrate that the country can move on from a fractious political environment in which single presidential terms repeatedly end in acrimony, impeachment or imprisonment.