Appellate jurisdiction describes a court’s power to hear and determine appeals from decisions of a lower court or tribunal, rather than to conduct an original trial of the facts. In legal practice it concerns reviewing alleged errors of law, procedure or (more rarely) fact, and may result in affirming, setting aside, varying, or remitting the decision under appeal.In the UK and Ireland the term is used descriptively across civil and criminal proceedings and is shaped by statute and case law governing each appeal route. The scope of appellate jurisdiction is defined by the relevant enabling legislation (for example, the Senior Courts Act 1981, Criminal Appeal Acts, devolution statutes, and equivalent Irish and Northern Irish legislation) and court rules, which specify who may appeal, time limits, grounds of appeal and available remedies.Usage is broadly consistent across England and Wales, Scotland, Northern Ireland and Ireland, although the structure of the appellate courts differs. Practitioners commonly distinguish between appeal as of right and appeal with permission/leave, and between first‑instance jurisdiction and appellate jurisdiction when advising on forum, standard of review, prospects of success, and costs and delay risks.