The judge's or jury's decision is not always final.  In most criminal cases, a decision at one level of the court system can be appealed to a higher level if there has been an error in law.

For example:

• If a person is found guilty of a crime and they disagree with that decision, an appeal can be made to a higher court to review the case.
• The higher court may agree with the judge's decision, or may change the decision, or order a new trial.
• The Crown prosecutor has the right to appeal if the offender is found not guilty.  If the offender is found guilty and receives a sentence that they feel is inappropriate, they can appeal the sentence.
• On the other hand, the Crown prosecutor may also appeal if they feel that the sentence is not suitable.

Witnesses rarely need to testify at the appeal court because the court uses the record (transcripts) to argue that there was an error in law.