Impleader, or third-party practice, is a procedure whereby a defendant may bring in a non-party liable to the defendant. What is the term for the original party who files the third-party action?

• A. Third-party plaintiff
• B. Third-party defendant
• C. Original plaintiff
• D. Intervenor

Answer: (A)

In impleader, the party who initiates the third-party action is called the third-party plaintiff. This is the defendant in the main action who claims that a nonparty is liable to them for all or part of the plaintiff’s claim and thus brings that nonparty into the case. The person brought in is the third-party defendant. The term reflects shifting potential liability, not the original role in the main case. Intervenors, by contrast, join for their own independent interest, not to shift liability. So the original party who files the third-party action is the third-party plaintiff.