What is double jeopardy?

The double jeopardy clause contained in the fifth amendment to the United States Constitution protects an accused individual against three things:

1. A second prosecution for the same offense after acquittal;
2. A second prosecution for the same offense after conviction; and
3. Multiple punishments for the same offense.

In deciding whether a previous prosecution for one offense bars a later prosecution for a different crime, a court must determine whether the two offenses are “different” using a test established by the U.S. Supreme Court in the 1932 decision of Blockburger v. United States.  That test focuses on whether each of the violated statutes requires proof of a fact which the other statute does not.  A single act may be an offense against two statutes, and if each statute requires proof of an additional fact which the other statute does not then an acquittal or conviction under either statute does not exempt the accused from prosecution and punishment under the other statute.