Joinder

Joinder is the joining of two or more legal issues, claims, or parties together so a court can hear them in a single proceeding rather than in separate, duplicative actions. In criminal law, joinder allows additional counts or additional defendants to be included in one indictment when the charges share common facts or form a series of similar offenses. In civil law, joinder of claims lets a plaintiff combine multiple claims against the same party in one action, a practice governed in United States federal courts by Rule 18 of the Federal Rules of Civil Procedure, without requiring the claims to be related. Joinder of parties covers combining multiple plaintiffs or defendants in one case, including permissive joinder under Rule 20 and compulsory joinder under Rule 19, the latter used when a party's interests would otherwise be left unprotected. Joinder agreements also appear in contract and trust law, binding a new party to an existing merger agreement or trust's terms, a common tool in mergers and acquisitions. Across these uses, joinder promotes efficiency and fairness by letting overlapping issues be resolved together.