When you are tried for a crime and are found innocent you may not be tried again for the same crime.
Guy 1: I am going to shoot you.
Guy 2: You will get arrested.
Guy 1: No I won't. I have been tried for murdering with a gun before and I was found innocent. They cannot try you twice for the same crime. It is called Double Jeoprady.
Guy 2: Oh crap