Benton v. Maryland

Double jeopardy, being subjected to trial for the same offense twice, is barred by the Fifth Amendment. Until Benton v. Maryland, this prohibition applied only to the federal government, not to the states. Under the principle of "dual sovereignty" (the separation of state and federal spheres of authority), however, there is no constitutional prohibition of federal prosecution for an offense after state prosecution for that offense; however, many states have laws barring state prosecution for an offense after federal prosecution has taken place.

An issue in double jeopardy is at what point jeopardy "attaches," that is, when a person may be considered to be in jeopardy. In jury trials, jeopardy attaches with the swearing in of the jury; in trials by judge it attaches with the swearing in of the first witness. The other major issue in double jeopardy is what actually constitutes double jeopardy, since a single incident may result in multiple charges against a person, and prosecutors have great discretion as to what charges they bring in a particular matter.