An appeal is the act or fact of challenging a judicially cognizable and binding judgment to a higher judicial authority. In common law jurisdictions, most commonly, this means formally filing a notice of appeal with a lower court, indicating one's intention to take the matter to the next higher court with jurisdiction over the matter, and then actually filing the appeal with the appropriate appellate court.

United States Appeals

The United States legal system generally recognizes two types of appeals: a trial de novo or an appeal on the record.

A trial de novo is usually available for review of informal proceedings conducted by administrative agency, referees, masters, commissioners, and some minor judicial tribunals in proceedings that do not provide all the procedural attributes of a formal judicial trial. If unchallenged, these decisions have the power to settle more minor legal disputes once and for all. If a party is dissatisfied with the finding of such a tribunal, one generally has the power to request a trial de novo by a court of record. In such a proceeding, all issues and evidence may be developed newly, as though never heard before, and one is not restricted to the evidence heard in the lower proceeding. Sometimes, however, the decision of the lower proceeding is itself admissible as evidence, thus helping to curb frivolous appeals.

In an appeal on the record from a decision in a judicial proceeding, both appellant and respondent are bound to base their arguments wholly on the proceedings and body of evidence as they were presented in the lower tribunal. Each seeks to prove to the higher court that the result they desired was the just result. Precedent and case law figure prominently in the arguments. In order for the appeal to succeed, the appellant must prove that the lower court committed reversible error, that is, an impermissible action by the court acted to cause a result that was unjust, and which would not have resulted had the court acted properly. Some examples of reversible error would be erroneously instructing the jury on the law applicable to the case, permitting seriously improper argument by an attorney, admitting or excluding evidence improperly, acting outside the court's jurisdiction, injecting bias into the proceeding or appearing to do so, juror misconduct, etc. The failure to formally object at the time to what one views as improper action in the lower court may result in the affirmance of the lower court's judgment on the grounds that one did not "preserve the issue for appeal" by objecting.

In cases where a judge rather than a jury decided issues of fact, an appellate court will apply an abuse of discretion standard of review. Under this standard, the appellate court gives deference to the lower court's view of the evidence and reverses its decision only if it was a clear abuse of discretion. This is usually defined as a decision outside the bounds of reasonableness. On the other hand, the appellate court normally gives less deference to a lower court's decision on issues of law and may reverse if it finds that the lower court applied the wrong legal standard.

In some rare cases, an appellant may successfully argue that the law under which the lower decision was rendered was unconstitutional or otherwise invalid, or may convince the higher court to order a new trial on the basis that evidence earlier sought was concealed or only recently discovered. In the case of new evidence, there must be a high probability that its presence or absence would have made a material difference in the trial. Another issue suitable for appeal in criminal cases is effective assistance of counsel. If a defendant has been convicted and can prove that his lawyer did not adequately handle his case and that there is a reasonable probability that the result of the trial would have been different had the lawyer given competent representation, he is entitled to a new trial.

An appellate court is a court that hears cases in which a lower court—either a trial court or a lower-level appellate court—has already made a decision, but in which at least one party to the action wants to challenge this ruling based upon some legal grounds that are allowed to be appealed either by right or by leave of the appellate court. These grounds typically include errors of law, fact, or due process.

In different jurisdictions, appellate courts are also called appeals courts, courts of appeals, superior courts, or supreme courts.

Who can appeal

A party who files an appeal is called an appellant, and a party on the other side is an appellee or respondent or, in some jurisdictions, the party who files is known as a petitioner and the party being sued is designated the respondent. Cross-appeals can also occur, when more than one party to a case is unhappy with the decision in some way, often when the winning party claims that more damages were deserved than were awarded.

An appeal as of right is one that is guaranteed by statute or some underlying constitutional or legal principle. The appellate court cannot refuse to listen to the appeal. An appeal by leave or permission requires the appellant to move for leave to appeal; in such a situation either or both of the lower court and the appellate court have the discretion to grant or refuse the appellant's demand to appeal the lower court's decision.

In tort, equity, or other civil matters, either party to a previous case may file an appeal. In criminal matters, however, the state or prosecution generally has no appeal as of right. And due to the double jeopardy principle, the state or prosecution may never appeal a jury or bench verdict. But in some jurisdictions, the state or prosecution may appeal as of right from a trial court's dismissal of an indictment in whole or in part or from a trial court's granting of a defendant's suppression motion. Likewise, in some jurisdictions, the state or prosecution may appeal an issue of law by leave from the trial court and/or the appellate court.

How an appeal is processed

Generally speaking, the appellate court examines the record of evidence presented in the trial court and the law that the lower court applied and decides whether that decision was legally sound or not. The appellate court will typically be deferential to the lower court's findings of fact (such as whether a defendant committed a particular act), unless clearly erroneous, and so will focus on the court's application of the law to those facts (such as whether the act found by the court to have occurred fits a legal definition at issue).

If the appellate court finds no defect, it "affirms" the judgment. If the appellate court does find a legal defect in the decision "below" (i.e., in the lower court), it may "modify" the ruling to correct the defect, or it may nullify ("reverse" or "vacate") the whole decision or any part of it. It may in addition send the case back ("remand" or "remit") to the lower court for further proceedings to remedy the defect.

In some cases, an appellate court may review a lower court decision de novo (or completely), challenging even the lower court's findings of fact. This might be the proper standard of review, for example, if the lower court resolved the case by granting a pre-trial motion to dismiss or motion for summary judgment, which is usually based only upon written submissions to the trial court and not on any trial testimony.

Another situation is where appeal is by way of re-hearing. Certain jurisdictions permit certain appeals to cause the trial to be heard afresh in the appellate court. An example would be an appeal from a Magistrate's court to the Crown Court in England and Wales.

Sometimes the appellate court finds a defect in the procedure the parties used in filing the appeal and dismisses the appeal without considering its merits, which has the same effect as affirming the judgment below. (This would happen, for example, if the appellant waited too long, under the appellate court's rules, to file the appeal.) In England and many other jurisdictions, however, the phrase appeal dismissed is equivalent to the U.S. term affirmed; and the phrase appeal allowed is equivalent to the U.S. term reversed.

Generally, there is no trial in an appellate court, only consideration of the record of the evidence presented to the trial court and all the pre-trial and trial court proceedings are reviewed—unless the appeal is by way of re-hearing, new evidence will usually only be considered on appeal in very rare instances, for example, if that material evidence was unavailable to a party for some very significant reason, such as prosecutorial misconduct.

In some systems, an appellate court will only consider the written decision of the lower court, together with any written evidence that was before that court and is relevant to the appeal. In other systems, the appellate court will normally consider the record of the lower court. In those cases, the record will first be certified by the lower court.

The appellant has the opportunity to present arguments for the granting of the appeal and the appellee (or respondent) can present arguments against it. Arguments of the parties to the appeal are presented through their appellate lawyers, if represented, or pro se if the party has not engaged legal representation. Those arguments are presented in written briefs and sometimes in oral argument to the court at a hearing. At such hearings, each party is allowed a brief presentation at which the appellate judges ask questions based on their review of the record below and the submitted briefs.

It is important to note that in an adversarial system, appellate courts do not have the power to review lower court decisions unless a party appeals it. Therefore, if a lower court has ruled in an improper manner or against legal precedent, that judgment will stand even if it might have been overturned on appeal.

In the United States, a lawyer traditionally starts an oral argument to any appellate court with the words "May it please the court."