Abstract: Is the United States at risk of democratic backsliding? And would the Constitution prevent such decay? To many, the 2016 election campaign may be the immediate catalyst for these questions. But it is structural changes to the socio-economic environment and geopolitical shifts that make the question a truly pressing one. This Article develops a taxonomy of different threats of democratic backsliding, the mechanisms whereby they unfold, and the comparative risk of each threat in the contemporary moment. By drawing on comparative law and politics experience, we demonstrate that there are two modal paths of democratic decay, which we call authoritarian reversion and constitutional retrogression. A reversion is a rapid and near-complete collapse of democratic institutions. Retrogression is a more subtle, incremental erosion that happens simultaneously to three institutional predicates of democracy: competitive elections; rights of political speech and association; and the administrative and adjudicative rule of law. Over the past quartercentury, we show that the risk of reversion has declined, while the risk of retrogression has spiked. The United States is not exceptional. We evaluate the danger of retrogression as clear and present, whereas we think reversion is much less likely. We further demonstrate that the constitutional safeguards against retrogression are weak. The near-term prospects of constitutional liberal democracy hence depend less on our institutions than on the qualities of political leadership and popular resistance.