If a defendant in a criminal prosecution is found guilty, the defendant can appeal the conviction (finding of guilt) or the sentence (punishment such as jail or prison, restitution, community service, probation, etc.). An appeal is not another trial—it is an opportunity to raise specific errors that might have occurred at trial. For example, a convicted defendant might claim on appeal that the judge made an incorrect ruling on an important question such as whether to exclude or suppress certain evidence, or whether to impose a certain sentence or punishment.

Appeals are complex processes and generally require the expertise of a licensed lawyer. On appeal a conviction may be reversed, a sentence may be altered, or the case may be sent back to the trial court for a new trial or a new sentence.

There are generally two potential levels of appellate review following a defendant’s conviction in a state court or federal trial court—an intermediate court (often called the court of appeals) and the highest court, or court of last resort (often the supreme court). Although a defendant usually has an automatic right to appeal a final conviction to the intermediate court of appeals, in many jurisdictions the highest court has discretion on whether to accept an appeal to review a case—known as discretionary review.

In Illinois, a defendant found guilty in a criminal prosecution has the right to appeal the conviction or the sentence. An appeal is not a new trial but a legal process to challenge potential errors made during the original trial, such as incorrect evidence rulings or sentencing decisions. Appeals require the expertise of an attorney and can result in a conviction being overturned, a sentence being changed, or the case being remanded for a new trial or sentencing. The first level of appellate review is the Illinois Appellate Court. If the appeal is unsuccessful there, the defendant can seek further review by the Illinois Supreme Court, which has discretionary power to choose which cases it will hear. The right to appeal to the intermediate appellate court is typically automatic, but the highest court's review is not guaranteed and is granted at the court's discretion.