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* Intended to ensure fair trials in the federal courts
* Once a person has been tried for a crime, he/she cannot be tried again for that exact same crime
* However,
* You can be tried in federal & state courts if you violate both federal & state laws in a single act
* A single act can also result in several criminal charges
* If a jury cannot agree on a verdict (hung jury), there is no jeopardy
* Appeals are not instances of double jeopardy either