states' rights

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun plural All rights not delegated to the federal government by the Constitution nor denied by it to the states.
• noun plural The political position advocating strict interpretation of the Constitution with regard to the limitation of federal powers and the extension of the autonomy of the individual state to the greatest possible degree.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun US, politics The belief that each of the 50 U.S. states has reserved powers, the sovereign right to determine policies on some issues.
• noun US, politics A catch phrase used by some in the Civil Rights Era as an excuse to keep the federal government from granting rights to black people by claiming such things were not federal issues.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun the rights conceded to the states by the United States constitution
• noun a doctrine that federal powers should be curtailed and returned to the individual states