Introduction. In the context of the COVID-19 pandemic announced by the WHO in 2020, American researchers bring up the question of the legitimacy, adequacy, or, on the contrary, redundancy of measures taken by the US leadership to protect the population. The study of the US President’s history of emergency powers can demonstrate how previous American Presidents managed to preserve or, conversely, subvert the established liberal foundations of American society in emergency situations. Methods and Materials. The author used methods of structural analysis and synthesis, historical and legal comparative method, formal legal method, and method of legal modeling. Analysis. The author studied A. Lincoln’s extra-constitutional authority to emancipate slaves, suspend the Habeas Corpus Act, create a volunteer army, and declare a naval blockade. On the basis of legal sources, we carried out the analysis of F. Roosevelt’s decisions on the creation of courts-martial and the internment of people of Japanese descent; reviewed the activities of G. Bush after the September 11 attacks and D. Trump’s emergency measures related to building the border wall in the south of the USA. Results. During the research, we found, that each military, economic, or social crisis increased the political significance and role of the executive branch in emergencies. We can characterize the increase of the emergency powers, delegated to the US Presidents, as steadily growing due to the crises that took place in various periods of American history. It was proved, that the precedents of emergency measures created by A. Lincoln, F. Roosevelt and George W. Bush had a long-term impact on the actions of the next US Presidents, opening up new legal opportunities for the use of emergency powers. At the same time, Congress and the US Supreme Court have taken a controversial stance on the validity of the President’s actions at various historical stages. Most of the time, the status of the legislative and judicial branches of government, as well as the understanding of “emergency situation” itself depended on the specific case and practical political needs.