Rule 14.Third-Party Practice

Enacted effective October 1, 2011 · Last verified June 26, 2026

In one sentenceRule 14 lets a defending party implead a nonparty who may be liable to it for all or part of the plaintiff’s claim — the classic “if I’m liable, then this third party owes me” move.

Full Text of Rule 14

Text sizeJump to: (a) (b)

(a) When a Defending Party May Bring in a Third Party.

(1) Timing of the Summons and Complaint. A defending party may, as third-party plaintiff, serve a summons and 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 14 days after serving its original answer.

(2) Third-Party Defendant’s Claims and Defenses. The person served with the summons and third-party complaint -- the “third-party defendant”:

(A) must assert any defense against the third-party plaintiff’s claim under Rule 12;

(B) must 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(g);

(D) may 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.

(3) Plaintiff’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 assert any defense under Rule 12 and any counterclaim under Rule 13(a), and may assert any counterclaim under Rule 13(b) or any crossclaim under Rule 13(g).

(4) Motion to Strike, Sever, or Try Separately. Any party may move to strike the third-party claim, to sever it, or to try it separately.

(5) Third-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.

(b) When a Plaintiff May Bring in a Third Party. When a claim is asserted against a plaintiff, the plaintiff may bring in a third party if this rule would allow a defendant to do so.

End

Plain-English Summary

Rule 14 is about impleader: bringing a new party into the lawsuit. A defending party, acting as a “third-party plaintiff,” may serve a summons and complaint on a nonparty who is or may be liable to it for all or part of the claim against it — think of an indemnitor, a guarantor, or an insurer. If the defendant files the third-party complaint within 14 days of serving its answer, no permission is needed; after that, it must obtain the court’s leave.

Once brought in, the third-party defendant must raise its defenses under Rule 12 and its counterclaims under Rule 13, may assert defenses and claims against the original plaintiff, and may even implead a further party. The plaintiff, in turn, may assert related claims against the third-party defendant. A plaintiff who is itself facing a claim may use Rule 14 just as a defendant would.

Frequently Asked Questions

What is impleader (a third-party complaint)?

It is when a defendant brings a nonparty into the case because that nonparty may be liable to the defendant for all or part of the plaintiff’s claim — for example, an indemnitor or insurer.

Do I need the court’s permission to file a third-party complaint?

Not if you file it within 14 days of serving your answer. After that, you must obtain the court’s leave by motion.

Can a plaintiff use Rule 14?

Yes. When a claim is asserted against the plaintiff (such as a counterclaim), the plaintiff may bring in a third party just as a defendant could.

Source & verification. Reproduced verbatim from the Montana Code Annotated as published by the State Law Library of Montana and the Montana Legislature. This rule has not been amended since its adoption. Adopted by the Supreme Court of Montana (AF 07-0157). Last verified June 26, 2026. · Official text

Also known as: impleaderthird-party complaintthird party practicethird party defendant