Many nation states have a two-tiered constitutional structure that establishes a superior state and a group of subordinate states that exercise overlapping control of a single population. The superior state (or what we will sometimes call the “superstate”) has a constitution (a “superconstitution”) and the subordinate states (“substates”) have their own constitutions (“subconstitutions”). One can call this constitutional arrangement “sub-national constitutionalism,” or, for short, “subconstitutionalism.”

Americans understand subconstitutionalism as federalism. The national government controls the superstate; each of the fifty states is a substate. Constitutions exist at both levels. Other states, including Germany, Australia, Austria, Argentina, Brazil, Ethiopia, Switzerland, Mexico, Russia, Venezuela, Malaysia, and Canada, also have federalist or quasi-federalist systems with two-tiered constitutional structures. The integration of Europe has produced a quasi-federalist system. EU members have retained their constitutions even as they increasingly submit to a European government with its own constitution...