The constitutional concept of double jeopardy, which prevents the government from prosecuting or punishing a defendant more than once for the same act, isn't nearly as simple as it sounds. Look here for information on the principles behind and application of the double jeopardy prohibition.
The Prohibition Against Double Jeopardy
The Fifth Amendment to the U.S. Constitution provides that no person shall “be subject for the same offence to be twice put in jeopardy of life or limb.”
Is the Movie 'Double Jeopardy' Based on Actual Law?
Some quick legal analysis of the movie 'Double Jeopardy'