Definition of Mistrial
A mistrial occurs if a trial is ended prior to its normal conclusion. A mistrial can occur for a variety of reasons including if a court lacks jurisdiction over the case, there was improper admittance of evidence or testimonies, there was misconduct of any individual that prevents due process, there is a hung jury (the jury cannot decide on a verdict), or there is a disqualification of a juror after the jury has been chosen (only if there is not an alternate juror and the parties cannot agree to continue with the case).
If a mistrial is declared by the judge it can be done with or without prejudice. If the judge declares a mistrial with prejudice the case cannot be retried again. If the judge declares a mistrial without prejudice the prosecution can decide whether or not to retry the case a second time.