In an ideal world, justice would be dispensed with unerring accuracy.
In the real world, procedural and/or legal errors sometimes lead to a miscarriage of justice in the trial courts. When a criminal defendant or a party in a civil action feels she has suffered such a miscarriage of justice, her only option is to appeal the decision to a higher court.
In most situations, appellate courts will not overrule the trial court's finding of fact. There is usually no opportunity to reexamine witnesses or review new evidence. Generally, the "record" of the lower court proceedings is all that the appellate court will review. Even if the appellate court is convinced that a procedural error or misinterpretation of the law was made, the appellant still needs to convince the court that the procedural error or legal misconception significantly affected the outcome of the case, or the appeal will not be granted. It takes strong persuasive abilities, particularly solid writing skills, in order to convince an appellate court to substitute its judgment for that of the lower court.
In addition to appeals, another form of appellate review is to petition the appellate court for a writ of mandate, prohibition or other extraordinary relief. This occurs a lower court or administrative agency has done something or failed to do something that will negatively affect the petitioner unless the appellate court intervenes. Needless to say, such relief is granted very sparingly.
Finally, if the appellant or petitioner is still not satisfied that justice has been served, he may be able to further to appeal the decision to the next highest court. For instance, if the California Court of Appeal rejects an appeal or writ the appellant or petitioner can petition the California Supreme Court for review of that decision. However, only cases of particular significance or those involving a conflict between lower courts are generally so reviewed.
NOTE: None of the information on this page should be taken as legal advice for any specific situations, nor can it substitute for consulting with an attorney.