Impleader refers to a procedural mechanism in civil litigation whereby a defendant, or a third-party defendant, can bring in another party, known as a third-party defendant, to the case. The purpose of the impleader is to shift some or all of the defendant's liability to the third-party defendant, and to avoid the need for multiple lawsuits over the same issue.
Under Federal Rule of Civil Procedure 14, a defendant may file a motion to implead a third-party defendant if that party may be liable for all or part of the plaintiff's claim against the defendant. The third-party complaint must assert a claim against the third-party defendant that arises out of the same transaction or occurrence that is the subject of the plaintiff's claim against the defendant.
See e.g. Caterpillar Inc. v. Lewis, 519 US 61 (1996).
[Last updated in February of 2023 by the Wex Definitions Team]