Rule 17.Plaintiff and Defendant; Capacity; Public Officers

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

In one sentenceRule 17 requires suits to be brought by the real party in interest, addresses who has capacity to sue, and provides for representation of minors and incompetent persons by guardians or a guardian ad litem.

Full Text of Rule 17

Text sizeJump to: (a) (b) (c) (d)

(a) Real Party in Interest.

(1) Designation in General. An action must be prosecuted in the name of the real party in interest. The following may sue in their own names without joining the person for whose benefit the action is brought:

(A) an executor;

(B) an administrator;

(D) a bailee;

(E) a trustee of an express trust;

(F) a party with whom or in whose name a contract has been made for another’s benefit; and

(G) a party authorized by statute.

(2) Action in the Name of the State of Montana for Another’s Use or Benefit. When a state statute so provides, an action for another’s use or benefit must be brought in the name of the State of Montana.

(3) Joinder of the Real Party in Interest. The court may not dismiss an action for failure to prosecute in the name of the real party in interest until, after an objection, a reasonable time has been allowed for the real party in interest to ratify, join, or be substituted into the action. After ratification, joinder, or substitution, the action proceeds as if it had been originally commenced by the real party in interest.

(b) Capacity to Sue or be Sued. Capacity to sue or be sued is determined by appropriate statutory provisions.

(1) With a Representative. The following representatives may sue or defend on behalf of a minor or an incompetent person:

(A) a general guardian;

(B) a committee;

(D) a like fiduciary.

(2) Without a Representative. A minor or an incompetent person who does not have a duly appointed representative may sue by a next friend or by a guardian ad litem. The court must appoint a guardian ad litem -- or issue another appropriate order -- to protect a minor or incompetent person who is unrepresented in an action.

(d) Public Officer’s Title and Name. A public officer who sues or is sued in an official capacity may be designated by official title rather than by name, but the court may order that the officer’s name be added.

End

Plain-English Summary

Rule 17 answers a basic question: who may bring or defend the suit? An action must be prosecuted by the real party in interest — the person who owns the right at stake — though certain fiduciaries (an executor, administrator, guardian, trustee of an express trust, and others) may sue in their own names. Importantly, a case can’t be dismissed for a real-party defect until, after an objection, a reasonable time has passed for the real party in interest to ratify, join, or be substituted into the action.

Capacity to sue or be sued is set by statute. For minors and incompetent persons, the rule allows a representative — a guardian, conservator, or similar fiduciary — to sue or defend; absent one, the person may proceed by a next friend or guardian ad litem, and the court must appoint a guardian ad litem — or issue another appropriate order — to protect an unrepresented minor or incompetent person. A public officer sued in an official capacity may be designated by title rather than by name.

Frequently Asked Questions

What is the “real party in interest”?

The person who owns the right being sued upon. A Montana action must be prosecuted in that person’s name, although certain fiduciaries may sue in their own names.

Can a case be dismissed for naming the wrong plaintiff?

Not immediately. After an objection, the court must allow a reasonable time for the real party in interest to ratify, join, or be substituted before dismissing.

How does a minor or incompetent person sue or get sued?

Through a representative such as a guardian or conservator, or by a next friend or guardian ad litem. The court must appoint a guardian ad litem — or issue another appropriate order — to protect an unrepresented minor or incompetent person.

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: real party in interestcapacityguardian ad litemnext friend