Federalism

Federalism is a political concept in which a group of members are bound together by covenant with a governing representative head.
Expressed Powers, Implied Powers, and Inherent Powers
The Divison of Powers assigns certain powers to the national government and others to the states.
The Supremacy Cluase establishes the U.S. Constitution, U.S. Treaties, and Federal Statutes as the supreme law of the land.
http://en.wikipedia.org/wiki/Federalism