Civil procedure

Third-Party Complaint

A third-party complaint brings a new party into an existing lawsuit because that party may be liable for the claim against the defendant.

Also called impleader. The defendant becomes a third-party plaintiff and the new party becomes a third-party defendant, who can then answer, counterclaim, and implead someone else in turn.

The theory has to be derivative: not merely that the newcomer is also at fault, but that it must reimburse the defendant if the defendant loses. That is why insurers, subcontractors, and component manufacturers are the usual arrivals.

It also extends the case. Every new party gets its own deadline to respond, its own discovery, and often its own motions, which is why a defendant weighs the delay against the value of spreading the liability. Timing matters: a defendant who serves a third-party complaint within fourteen days of its answer needs no permission, and after that it takes leave of court, which judges weigh against the delay it will cause.