What do you think would happen to the criminal justice system if the ban on double jeopardy were removed?

You would have a lot more abuses from prosecutors. Believe it or not, the double jeopardy law was created to protect the criminals and not the system. It says that a person cannot be tried twice for the same crime. This is to prevent a prosecutor from basically bringing someone to trial 800 times in a row to try and hope that one jury out of all of those will find him guilty. Basically, it tells a prosecutor that he had better have his ducks all lined up before proceeding with the trail.