If a defendant in a criminal prosecution for DUI/DWI 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 California, a defendant convicted of DUI/DWI has the right to appeal the conviction or the sentence. The appeal is not a new trial but a legal process to identify and argue errors made during the original trial, such as improper evidence rulings or sentencing issues. Appeals require the skills of an attorney due to their complexity. If successful, an appeal may result in the reversal of the conviction, modification of the sentence, or a remand for a new trial or sentencing. The first level of appellate review is typically the California Court of Appeal. If the appeal is unsuccessful at this intermediate level, the defendant can petition the California Supreme Court, which has discretionary power to decide whether to review the case. The right to appeal to the intermediate appellate court is automatic, but review by the state's highest court is not guaranteed.