coplaintiff

Coplaintiff is a person or entity that joins with one or more other plaintiffs to bring a civil action. The term is commonly written as co-plaintiff or co-plaintiffs, and it denotes plaintiffs who share a common claim or closely related claims against a defendant. A coplaintiff typically participates in the lawsuit alongside other named plaintiffs, either filing a single joint complaint or coordinating separate complaints within the same action.

The concept arises from rules governing joinder of parties in civil procedure. In many jurisdictions, including the United States, permissive joinder allows plaintiffs whose claims arise from the same transaction or occurrence and involve common questions of law or fact to sue together. Courts may permit, or require, coordination or consolidation to streamline proceedings. Coplaintiffs may be represented by one attorney or by separate counsel, depending on potential conflicts of interest and procedural arrangements. If the plaintiffs’ claims differ in scope or requested relief, the court may manage multiple theories of liability and damages within the same action.

Advantages of having coplaintiffs include efficiency in discovery, shared investigation costs, and the potential to present a broader or stronger set of allegations. Disadvantages can include conflicts of interest among plaintiffs, more complex litigation management, and challenges in settling or allocating damages fairly among the plaintiffs. Class actions are related but distinct, as they involve a defined group of unnamed plaintiffs represented by a named representative rather than multiple individually named plaintiffs.

See also: co-plaintiff, joinder, class action, joint plaintiff, representative plaintiff.