R 1011.Successive third-party proceedings; counterclaims

Third-party practice doesn't stop at one layer. CPLR 1011 lets a third-party defendant who thinks someone else is or may be liable for all or part of the third-party claim bring that new person into the case, following the same procedure CPLR 1007 sets for the original defendant's third-party complaint. That means a chain of impleader is possible: a defendant brings in a third-party defendant, who in turn brings in a fourth-party defendant, and so on, each layer governed by the same rules.

The second half of the rule addresses a different situation: a plaintiff who becomes the target of a counterclaim. Once a defendant asserts a counterclaim against the plaintiff, the plaintiff -- now defending against a claim just as any defendant would -- can proceed under CPLR 1007 as though it were the defendant in that posture, impleading someone who may be liable for the counterclaim.

The section keeps the underlying framework consistent no matter which party ends up defending a claim. Whether the party facing potential liability is the original defendant, a third-party defendant one or more layers deep, or a plaintiff answering a counterclaim, the same third-party procedure applies.