dual sovereignty

political subdivisions of States—counties, cities, or whatever—never were and never have been considered as sovereign entities; they have been traditionally regarded as subordinate governmental instrumentalities created by the State to assist in the carrying out of state governmental functions, making a dual sovereignty theory an anachronism as applied to municipal and state courts within a single State

Defined by the Supreme Court in - Waller v. Florida, 397 U.S. 387 (1970).