Rule 17.Plaintiff and defendant; capacity

Title IV: Parties · Last amended July 1, 2016 · Last verified July 14, 2026

In one sentenceRule 17 requires that a lawsuit be brought in the name of the person who holds the right being sued on, while letting representatives like executors and trustees sue in their own names and giving minors, incompetent persons, and unknown heirs a path into court.

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 guardian;

(E) a bailee;

(F) a trustee of an express trust;

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

(H) a party authorized by statute.

(2) Action in the name of the State of Idaho for another's use or benefit. When a statute of the State of Idaho so provides, an action for another's use or benefit must be brought in the name of the State of Idaho.

(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. The capacity of a party, who is not acting in a representative capacity, to sue or be sued, is determined by the law of this state.

(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) Unknown owners or heirs as parties. All persons who are or may be interested in the subject matter of an action whose names are unknown to the plaintiff may be made parties by being named and described as unknown owners or unknown heirs or unknown devisees of any deceased person. The unknown parties may be designated in the complaint, counterclaim or cross-claim, or in an amendment of any of these. This rule applies in all actions or proceedings:

(1) to obtain title or possession,

(2) to remove adverse claim or title or to quiet title,

(3) for partition,

(4) for sale,

(5) to foreclose any incumbrance,

(6) to enforce any trust,

(7) for specific performance of any contract, or

(8) for any other disposition of any property, real, personal, or mixed, situated within the State of Idaho, including causes of action, either situated within or due or claimed to be due from persons, firms or corporations resident within the State of Idaho.

End

Amendment History

(Adopted March 1, 2016, effective July 1, 2016.)

Plain-English Summary

Rule 17 says a case has to be brought by the person who owns the claim, not a stranger to the dispute. That keeps a defendant from being sued twice over the same wrong and confirms the plaintiff has enough stake in the outcome to see the suit through. The rule carves out several fiduciaries and representatives, executors, administrators, guardians, bailees, and trustees among them, who may sue in their own name on behalf of someone else's interest, along with anyone authorized by statute to do the same. If a case gets filed in the wrong name, the court cannot toss it out immediately; it must give the real party in interest a reasonable chance to step in, ratify the suit, or be substituted before dismissal, and once that happens the case proceeds as though it had started that way.

Whether someone has the legal capacity to sue or be sued in the first place is governed by Idaho law. For minors and incompetent persons, the rule looks first to whoever already holds legal authority over them, a general guardian, conservator, or similar fiduciary, and if no one holds that role, the court appoints a guardian ad litem or a next friend to protect their interests in the litigation. Rule 17 also solves a practical problem in property disputes: when an action involves title, partition, foreclosure, or similar claims to Idaho property and some interested parties are unidentifiable, they can be named and served as unknown owners, heirs, or devisees rather than holding up the case indefinitely.

Frequently Asked Questions

What does "real party in interest" mean?

It means the person or entity that holds the substantive right being enforced in the lawsuit, as opposed to someone with no direct stake in the outcome.

Can an executor or trustee sue without naming the person they represent?

Yes. Rule 17 lists executors, administrators, guardians, bailees, trustees of express trusts, and similarly authorized parties who may sue in their own name.

What happens if a case is filed in the wrong party's name?

The court can't dismiss it right away. It must give the real party in interest a reasonable time to ratify, join, or be substituted into the case first.

Who sues on behalf of a child or a person who can't manage their own affairs?

A general guardian, conservator, or similar fiduciary sues or defends for them. If none exists, the court appoints a guardian ad litem or allows suit by a next friend.

How do you sue someone whose identity you don't know, like an unknown heir?

In property-related actions covering title, partition, foreclosure, and similar claims, unidentified interested persons can be named and served as unknown owners, heirs, or devisees.

Source & verification. Rule text are reproduced verbatim from the Idaho Rules of Civil Procedure, adopted by the Supreme Court of Idaho. Last verified July 14, 2026. · Official source

Also known as: real party in interestwho can sue in idahoguardian ad litem rulecapacity to sue or be suedunknown heirs lawsuitnext friend for a minor