Final answer:
The principle of Federalism in the U.S. Constitution directly addresses the relationship between the national and state governments, outlining the balance and hierarchy of authority, with the national government typically holding supremacy in conflicts.
Step-by-step explanation:
The constitutional principle that most directly addresses the relationship between the national and state governments is Federalism. This principle is the foundation of the constitutional framework that balances the powers between the national government and the states. It delineates how powers are allocated to each level and how they must interact with one another. The Constitution's provisions serve as guidelines for their interactions, ensuring a clear hierarchy where federal laws generally supersede state laws under the supremacy clause.
Furthermore, the principle of national supremacy, established in court rulings, highlights that legitimate national laws take precedence over conflicting state laws. Over time, the balance of power between national and state authority has evolved through legal decisions, reflecting the changing needs and attitudes of society. The U.S. Constitution and subsequent legal interpretations largely shape these dynamics, allowing for a balance between decentralized and centralized governance.