Rules of court are the procedural rules governing how litigation is conducted in a particular court, including how to start and defend proceedings, time limits, service of documents, evidence, interlocutory applications, hearings, appeals and enforcement. They structure civil and criminal procedure and ensure fair, efficient and consistent case management. In England and Wales, the principal sets are the Civil Procedure Rules (CPR), Criminal Procedure Rules (CrimPR) and Family Procedure Rules (FPR), supported by practice directions. In Scotland, procedure is governed mainly by the Rules of the Court of Session and the Ordinary Cause Rules, together with sheriff court and specialist court rules. In Northern Ireland, the Rules of the Court of Judicature and county court rules perform an equivalent function. In Ireland, the Rules of the Superior Courts, Circuit Court Rules and District Court Rules apply. Rules of court are made under statutory powers (for example, by rules committees or the Civil Procedure Rule Committee) and interpreted by case law. Compliance is mandatory: breach can lead to sanctions such as strike‑out, wasted costs, unless orders, or other case management penalties.