Rule 14: Third-Party Practice (Impleader)

Impleader under Rule 14 lets a defendant bring a new party into the lawsuit — someone the defendant claims is responsible for all or part of what the defendant might owe to the plaintiff. The classic example is an indemnity or contribution claim: if the plaintiff sues a general contractor, the contractor can implead a subcontractor whose work actually caused the injury.

The key limitation is that impleader is only proper when the third-party defendant's liability is derivative of the original claim. You cannot use Rule 14 simply because a third party might also be liable to the plaintiff on an independent basis. The third-party claim must be that 'if I am liable to the plaintiff, then this third party is liable to me.'

Once impleaded, the third-party defendant gains significant procedural rights: they can assert defenses to the third-party claim, file counterclaims and crossclaims, and even assert defenses that the original defendant has against the plaintiff. The plaintiff may also assert claims directly against the third-party defendant if those claims arise out of the same transaction or occurrence.