In one sentenceRule 14 lets a defending party bring in a nonparty who may owe it all or part of what's being claimed, sets out what claims and defenses everyone involved can then assert against each other, and gives the court power to strike, sever, or separately try the third-party claim.
aWhen a defending party may bring in a third party.
1Timing of the summons and third-party complaint. A defending party may, as a third-party plaintiff, serve a summons and third-party complaint on a nonparty who is or may be liable to it for all or part of the claim against it. But the third-party plaintiff must, by motion, obtain the court’s leave if it files the third-party complaint more than 10 days after serving its original answer.
2Third-party defendant’s claims and defenses. The person served with the summons and third- party complaint—the “third-party defendant”:
Amust defend against the third-party plaintiff’s claim under Rules 8 and 12;
Bmust assert any counterclaim against the third-party plaintiff under Rule 13(a), and may assert any counterclaim against the third-party plaintiff under Rule 13(b) or any crossclaim against another third-party defendant under Rule 13(f);
Cmay assert against the plaintiff any defense that the third-party plaintiff has to the plaintiff’s claim; and
Dmay also assert against the plaintiff any claim arising out of the transaction or occurrence that is the subject matter of the plaintiff’s claim against the third-party plaintiff.
3Plaintiff’s claims against a third-party defendant. The plaintiff may assert against the third-party defendant any claim arising out of the transaction or occurrence that is the subject matter of the plaintiff’s claim against the third-party plaintiff. The third-party defendant must then defend against the plaintiff’s claim under Rules 8 and 12 and assert any counterclaim under Rule 13(a), and may assert any counterclaim under Rule 13(b) or any crossclaim under Rule 13(f).
4Motion to strike, sever, or try separately. Any party may move to strike the third-party claim, to sever it, or to try it separately.
5Third-party defendant’s claim against a nonparty. A third-party defendant may proceed under this rule against a nonparty who is or may be liable to the third-party defendant for all or part of any claim against it.
bWhen a plaintiff may bring in a third party. When a claim is asserted against a plaintiff, the plaintiff may bring in a nonparty as a third party if this rule would allow a defendant to do so.
Amendment History
Promulgated by R-16-0010, effective January 1, 2017.
Plain-English Summary
A defending party may serve a summons and third-party complaint on someone outside the case who is or may be liable for all or part of the claim against it, though court permission is required if more than 10 days have passed since the original answer was served. The person brought in this way — the third-party defendant — must defend against that claim the same way any defendant would, must assert any compulsory counterclaim against the third-party plaintiff and may assert a permissive one, and may raise against the original plaintiff any defense the third-party plaintiff has, plus any claim arising from the same transaction as the plaintiff's claim.
The plaintiff, in turn, may assert against the third-party defendant any claim arising from that same transaction, and the third-party defendant must then defend against it and assert compulsory counterclaims the same way. Any party may move to strike the third-party claim, sever it, or have it tried separately, and a third-party defendant facing its own exposure may bring in a further nonparty under this same process.
A plaintiff can use this same mechanism in reverse — bringing in a third party under the same conditions that would let a defendant do so — when a claim is asserted against that plaintiff.
Frequently Asked Questions
Who can a defendant bring into a lawsuit as a third-party defendant?
A nonparty who is or may be liable to the defendant for all or part of the claim against it.
Does a defendant need permission to file a third-party complaint?
Only if more than 10 days have passed since the defendant served its original answer; otherwise no court order is required.
Can the original plaintiff bring a claim directly against the third-party defendant?
Yes, for any claim arising out of the same transaction or occurrence as the plaintiff's claim against the third-party plaintiff.
Can a plaintiff also use third-party practice?
Yes, a plaintiff facing a claim may bring in a third party under the same rules that would allow a defendant to do so.
Source & verification. The rule text and History are reproduced verbatim from the
official Arizona Rules of Civil Procedure (Ariz. R. Civ. P. 14). Prescribed by the Supreme Court of Arizona (Ariz. Const. art. 6, § 5). The plain-English summary is original and written by us. Last verified July 1, 2026. ·
Official source
Also known as:third-party complaintimpleaderthird-party defendant