July 16, 2014
Double jeopardy is the principle that a defendant should not be tried twice for the same crime once he is either acquitted or convicted (or pleads guilty).
The principle applies slightly differently in the United States because of the principle of dual sovereignty. Each state and the federal government is a separate sovereign, therefore, it does not violate double jeopardy for different states to try someone twice for the same underlying crime. Similarly, a state and the federal government may put someone on trial for the same crime. But the same state cannot try a person twice for the same crime and the federal government cannot try someone twice for the same crime after a conviction or acquittal.
Below is a short video on how double jeopardy applies in the United States.