On all fours describes a previous case whose facts and legal issues are so closely analogous to the current case that the earlier decision is directly applicable and highly persuasive, or binding where precedent rules apply. In practice across England and Wales, Scotland, Northern Ireland and Ireland, the phrase is a descriptive common law expression rather than a statutory term. Courts and practitioners use it in judgments, pleadings and submissions to argue that an authority is factually and legally indistinguishable from the case at hand. A case said to be “on all fours” will usually carry significant weight in legal reasoning, limiting a court’s ability to distinguish it and reinforcing the doctrine of precedent. Conversely, a party may contest that a cited authority is not “on all fours” by identifying material differences in facts, legal context, remedy sought or applicable statutory framework. Usage is broadly consistent across the UK and Irish jurisdictions, including in civil, criminal, public and commercial law, wherever case law is relied upon to support argument, advise clients, predict outcomes or assess litigation risk.