This work offers a new democratic case for federalism, understood as a form of governance in which multiple entities in a country possess final decision-making authority (viz., can make decisions free from others substituting their decisions, issuing fines, etc.) over at least one subject (e.g., immigration, defense). It argues that leading solutions to the democratic boundary problem provide overlapping arguments for federalism. The underlying logic and many details of the most commonly cited solutions focused on those relevantly affected by and (...) subject to decisions each support three distinct arguments (focused on voteshares, other forms of democratic influence, and persistent minorities) for multiple demoi possessing authority in a polity. Federalism is the best available method for recognizing the distinct demoi. This not only supports federal governance as opposed to unitary governance and subsidiarity. It also suggests that democracy and federalism are importantly related and have several implications for institutional design. (shrink)