Will democratic countries ever be the same after COVID-19? By identifying common trends and issues in legal responses to COVID-19 at the comparative level, this Article tries to answer this crucial question by analyzing the long-term effects of the pandemic. In particular, this work examines whether (and how) institutional disruptions, new dynamics among government levels, and serious limitations of rights and freedoms will permanently affect some basic principles, considered as the “common” foundations of contemporary constitutionalism. These principles are the horizontal separation of powers, including the principle of legality, vertical separation of powers, entailing legal certainty, and constitutional reviewability, at the heart of the rule of law. The claim of this Article is that COVID-19 was a “game-changer” for public law and, at the same time, it taught us some “lessons” that could be useful to tackle forthcoming global emergencies.