Immediately after judgment is granted, the losing party may ask the court of first instance to reconsider, giving it a chance to correct its own errors. In Anglo-American courts this procedure is known as a motion for a new trial. In some cases (e.g., if there is newly discovered evidence), procedures analogous to motions for a new trial exist in European countries. If such a move fails, all legal systems permit a losing party to appeal the adverse judgment to another court. They differ as to which judgments may be appealed and how deeply the appellate court will scrutinize whichever judgments are appealed.

In general, appellate courts in civil-law systems exercise broad supervisory authority over lower court rulings. Appeals to intermediate appellate courts from courts of first instance are available quite broadly in civil-law systems, frequently for all judgments exceeding a certain amount and at times for certain types of judgments regardless of the amount. Because the appeal involves a new hearing of the case, the procedure resembles that used by courts of first instance, though entirely new claims may not be presented. In the case of a review of a nonfinal judgment, the appellate court frequently limits its review to an examination of the legal correctness of that judgment and then remands the case, so that proceedings in the court below may be completed. Appeals to the supreme courts of the civil-law countries generally are limited to questions of law. The facts are not ordinarily reexamined, and no new evidence may be introduced. In several countries (e.g., France and Italy), the arguments by the parties may be augmented by an officer representing the Ministry of Justice. If a court reverses a lower court ruling, it generally does not substitute its own judgment for the erroneous judgment below but merely annuls the erroneous judgment and remands the case for new proceedings, frequently to a court different from that from which the case came. Review by supreme courts usually can be sought for all final (and sometimes even nonfinal) decisions of intermediate appellate courts

By contrast with civil-law regimes, common-law appellate courts reverse only if a harmful error (one deemed likely to have affected the judgment) has occurred, and even then only if the appealing party complained about that error to the trial court at the time of its ruling. Common-law appellate courts review errors of law as well as fact but may reverse only if convinced that the lower court’s finding of law was erroneous or a finding of fact (whether by judge or jury) was clearly erroneous. Even then the appellate court will still affirm if the trial court reached the correct result. This preference for affirmation is reinforced by the rule that appellate courts in common-law systems consider only the record and transcript of evidence in the trial court and receive no new evidence. Combined with the general rule that only final judgments may be appealed, these rules make it typically more difficult for a losing party to secure appellate reversal in common-law regimes. Most common-law jurisdictions provide a second appellate court to which a party may appeal from an adverse decision of the first appellate court. The right to such a second appeal generally is limited to certain types of cases raising particularly important issues, and only a small percentage of litigants are permitted to pursue a second appeal. In the U.S. Supreme Court, a petition to authorize an appeal is known as a petition for a writ of certiorari.

Appellate courts universally are constituted of several judges. It is frequent practice in Anglo-American countries for judges who disagree with the decision of the majority of the hearing panel to prepare and file dissenting or separate concurring opinions, in which they explain the reasons for their disagreements. In civil-law countries, such dissenting opinions are rarely allowed; indeed, the courts are generally forbidden to disclose the position taken by an individual member.