On December 3, 2024, South Korean President Yoon Suk-yeol attempted to seize control of the country by abruptly declaring martial law. What happened next reveals how democracies can unleash antibodies to resist dangerous threats to the body politic and defend their system of government. Although Yoon had sent military forces to surround the National Assembly and block legislators from taking an emergency vote rescinding his order, legislators rushed to the building and were able to enter.