On Dec. 3, 2024, South Korean President Yoon Suk-yeol declared martial law – a scenario that seemed unimaginable in the prosperous and thriving democracy. National Assembly members from all political parties overturned the martial law decree within hours, and South Korea narrowly averted a return to military rule.
Yoon survived a Dec. 7 impeachment vote, but in a second vote on Dec. 14, the National Assembly voted to impeach the president, suspending Yoon from office.
This time, enough legislators from Yoon’s own party agreed to impeach him.
South Koreans have strong feelings about authoritarian rule
The declaration of martial law and the Decree by the Martial Law Commander echoed dark chapters from South Korea’s past. Many in South Korea remember the military coups and authoritarian regimes that stifled democracy prior to the country’s democratization in 1987. The specter of tanks rolling into city streets was not a distant memory but a lived experience – or a well-taught lesson in their national consciousness. Even for the younger generation born long after democratization, textbooks, movies – and news stories about ongoing truth and reconciliation efforts – are a constant reminder of South Korea’s long history of political suppression.
Soon after the declaration of martial law, and dispatch of armed troops and police to the National Assembly, social media was flooded with reminders of the 1980 Gwangju Uprising and Massacre. Urgent calls to prevent history from repeating itself and collective memories about the past helped fuel an immediate and unified public outcry the night of Dec. 3. Lawmakers from all parties, along with civil society groups and everyday citizens, sprang into action after the martial law announcement near midnight, organizing protests and flooding social media with calls for vigilance. The message from South Korean citizens was clear: Do not return to military rule.
Holding Yoon accountable
This remarkable overnight episode underscores how deeply democracy has taken root in South Korea. But the events of the past 10 days have also exposed vulnerabilities within the country’s political system – and the precariousness of South Korea’s democracy. First and foremost, the ruling People Power Party (PPP) did not endorse the first impeachment proceedings. This was surprising, as 18 out of 108 PPP lawmakers had swiftly gathered at the National Assembly the night of Dec. 3 to vote to overturn martial law.
Despite clear evidence that the president and his closest allies, including the minister of defense, covertly planned and executed an emergency martial law declaration out of “frustration with the opposition,” the PPP refused to even participate in the initial impeachment vote – the only constitutional mechanism to suspend the president’s duties and hold Yoon accountable for the self-coup attempt. When that impeachment bill was finally put to a vote on the night of Dec. 7, it failed to pass, falling short of the required two-thirds majority because of the abstentions of PPP lawmakers.
To be clear, senior PPP members, including party leader Han Dong-hoon, quickly reached consensus that the president could no longer carry out his duties. However, they fiercely resisted impeachment because that would mean transferring presidential power to the opposition Democratic Party, which holds 60% of the legislative seats.
Growing public pressure and internal dissent within the PPP led to the second vote for impeachment on Dec. 14 to pass the legislature, where 204 out of 300 lawmakers, including 12 from the PPP, voted in favor of impeachment. This decision suspended President Yoon from office. The final ruling will be made by the Constitutional Court within up to 180 days to decide whether to remove him permanently. In the interim, Prime Minister Han Duck-soo assumed the role of acting president.
The PPP has struggled for nearly a decade
For the PPP and South Korea’s broader conservative political bloc, the aftermath of the martial law crisis evoked the winter of 2016, when mass protests following political scandal and corruption accusations culminated in the impeachment of President Park Geun-hye. The conservative party, operating as the Saenuri Party at that time, fractured deeply and eventually rebranded itself as the Liberty Korea Party and, later, as the People Power Party.
But South Korea’s conservative politicians never recovered the public’s trust or voter support. In 2020, the PPP and its satellite party won 103 seats out of 299 National Assembly seats, marking the worst result for conservatives since 1960. The Democratic Party, meanwhile, claimed 180 seats. In 2024, the voting outcome was similar. Though Yoon, the PPP presidential candidate, had won the 2022 election, PPP legislators won just 108 seats in the National Assembly, while the Democratic Party again won 180 seats.
After the Dec. 7 impeachment vote failed, mass protests on the streets condemned the PPP for putting partisan interests before democratic principles and the constitution. Many South Koreans began to call the party itself unconstitutional.
Is South Korea’s democracy in danger?
Yoon’s declaration of martial law and the impeachment votes that followed highlight both the resilience and precariousness of Korean democracy, underscoring its structural vulnerabilities and institutional frailties. South Korea is one of the few OECD member countries – alongside the United States, Mexico, Costa Rica, and Turkey – to operate under a presidential system. The current Korean constitution, adopted in 1987, reflects decades of democratic struggle – and the people’s aspiration for a more accountable and democratic political system. The constitution incorporates principles such as the separation of powers, along with institutional rules designed to limit presidential authority and strengthen checks and balances on political power.
South Korea’s painful history of authoritarianism led to these constraints on unilateral presidential power. However, the events following democratization – and the recent declaration of martial law – reveal that South Korea’s institutional framework still lacks the resilience needed to guarantee the stable and uninterrupted functioning of democracy.
The National Assembly’s constitutional power to impeach the president is intended to prevent unilateral and extreme actions, such as declaring martial law without an imminent threat, by creating the expectation of institutional sanctions. In other words, the threat of impeachment is supposed to deter extreme actions outright. Yet, despite these safeguards, the president declared martial law unexpectedly, and the opposition party was compelled to pursue impeachment proceedings. Why did the institutional guardrails and the tools of separation of powers fail to function as intended?
Loyalty tests erode the legislature’s role in counterbalancing the president
Some might attribute this political crisis to the personal misconduct of Yoon and his associates, arguing that reshuffling personnel or replacing leadership would stabilize democracy. However, this diagnosis overlooks the institutional foundations of democracy. Regardless of who holds power – and whether that individual is self-serving or outright malevolent – democratic institutions by design must make anti-democratic actions difficult to execute.
In South Korea, the legislature, as a core pillar of democracy, plays a critical role in maintaining these checks and balances. Legislators from the president’s own party are especially crucial in an era of extreme polarization and gridlock. Their honest advice and political judgment can serve as an important check on a president inclined toward unaccountable or reckless unilateral actions.
The effective exercise of the legislature’s constitutional authority to check presidential power is critical for deterring abuses of power. Unfortunately, legislators from Yoon’s own party largely abdicated this responsibility. Rather than fulfilling their constitutional duty, they aligned themselves with Yoon to secure his endorsement, seeking favorable treatment during party primaries, and cabinet positions once he assumed office in 2022. This surrender of legislative independence has rendered a key institutional safeguard ineffective.
Yoon has rewarded those loyal to him – and punished dissenters. While loyalty tests to reward and punish legislators are not unprecedented in the South Korean presidency, the PPP faction that supports Yoon has gone further, prioritizing internal party power struggles over their constitutional obligation to check the president’s actions. This dynamic has weakened the legislature’s role as a critical counterbalance to executive power.
Another reason the National Assembly in South Korea struggles to effectively check presidential power lies in the misalignment of electoral cycles. South Korea’s president serves a single 5-year term, while legislative elections occur every 4 years. This mismatch prevents the midterm elections from serving as a proper accountability mechanism. For instance, legislative elections might occur a year after a presidential election – when the president wields significant power. Or elections might take place right before the presidential election, when major party nominees dominate the nomination process for the legislative election.
The broader message about political power
South Korea’s recent political crisis offers important lessons on the separation of powers – and the tools that are needed to constrain the unilateral actions of top political leaders worldwide. Across the globe, when democracy faces a crisis, a prevailing narrative often credits citizens with saving it. This is particularly true in South Korea, where fierce citizen protests and resilience have repeatedly safeguarded democracy. The country’s history is rich with examples: the April Revolution of 1960, which ended Syngman Rhee’s autocratic presidency after electoral fraud; the Gwangju uprising of 1980, a bold stand against Chun Doo-hwan’s military regime; the June 1987 Democratic Uprising, which paved the way for democratization; and the Candlelight Protests of 2016-2017, which led to the impeachment of President Park Geun-hye. These movements demonstrate the power of collective action in preserving democratic principles amid repression, corruption, and political crises.
This time, South Korean citizens once again mobilized, demanding the resignation and impeachment of President Yoon and denouncing the declaration of martial law. While these actions highlight the critical role of civic engagement in preserving democracy, relying solely on citizen activism is insufficient. A robust legislative body that both collaborates and competes with the executive branch – and remains independent of presidential pressure – is essential to curbing unilateral presidential moves. Executive overreach is a hallmark of democratic backsliding.
Any democracy can be at risk
In the context of the United States, the 2024 Supreme Court decision in Trump v. United States significantly expanded the scope of presidential immunity, granting absolute protection for actions within a president’s exclusive constitutional authority and presumptive immunity for other official acts. To many Americans, this ruling raises new concerns about potential abuses of presidential power, and about weakened checks and balances. Trump’s focus on loyalty in appointments and endorsements, coupled with the influence of a substantial congressional MAGA faction within the Republican Party, underscores the danger of eroded legislative checks on presidential power that could heighten the risk of reckless unilateral actions.
South Korea’s martial law declaration, similarly, demonstrates that even in established democracies, failed accountability and deterrence efforts by the legislature can enable dangerous executive overreach. To uphold democratic principles and prevent the concentration of unchecked power, the legislature – including members of the president’s own party – must be willing to act as a genuine check on the executive.
Ji Yeon Hong is an associate professor of political science and Korea Foundation Professor of Korean Studies at the University of Michigan.
Hye Young You is an associate professor in the Department of Politics and School of Public and International at Princeton University.
