Joinder of parties
The procedural mechanism allowing multiple claimants or defendants to participate in one action when their claims are sufficiently connected.
Joinder of parties lets several persons sue or be sued in the same proceeding, improving efficiency and reducing inconsistent judgments when claims share facts, legal issues, or relief. Common-law systems distinguish permissive and required joinder. Swiss civil procedure uses concepts such as simple or necessary joinder of parties, depending on whether joint proceedings are optional or required because the legal relationship must be decided uniformly. Joinder affects jurisdiction, costs, representation, procedural acts, and the scope of the judgment.