Rule 17.Plaintiff and defendant; capacity; public officers

Group IV: Parties · Last amended March 1, 2017 · Last verified July 14, 2026

In one sentenceRule 17 requires a civil action to be brought in the name of the person who holds the right being sued on, while spelling out who may sue in a representative capacity and how capacity to sue or be sued is determined.

Full Text of Rule 17

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

(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 United States for Another’s Use or Benefit. — When a federal statute so provides, an action for another’s use or benefit must be brought in the name of the United States.

(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. —

(1) The capacity of an individual, including one acting in a representative capacity, to sue or be sued, shall be determined by the law of this State.

(2) A married person may sue or be sued in all respects as if he or she were single.

(3) The capacity of a corporation to sue or be sued shall be determined by the law under which it was organized, unless a statute of this State provides to the contrary.

(4) A partnership or other unincorporated association may sue or be sued in its common name.

(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, or if such representative fails to act the minor or incompetent person 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) Suing person by fictitious name. — When the identity of a defendant is unknown, such defendant may be designated in any pleading or proceeding by any name and description, and when the true name is discovered the pleading or proceeding may be amended accordingly; and the plaintiff in such case must state in the complaint that the plaintiff could not discover the true name, and the summons must contain the words, ‘real name unknown‘, and a copy thereof must be served personally upon the defendant.

(e) 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

Amendment History

Added February 2, 2017, effective March 1, 2017.

Plain-English Summary

Rule 17 requires that a lawsuit be brought by the person who holds the right being enforced — the real party in interest — not by a stranger to the claim. The rule then lists people who can sue in their own name even though the recovery ultimately benefits someone else: an executor, administrator, guardian, bailee, or trustee, along with anyone who signed a contract for another's benefit or who has statutory authority to sue. If a case gets filed in the wrong name, the court cannot dismiss it outright; it must give the real party in interest a chance to step in, ratify the suit, or replace the original plaintiff, after which the case moves forward as though it had started that way.

The rule also fixes who has the legal capacity to sue or be sued. For an individual, capacity turns on state law, and a married person can sue or be sued as if single. A corporation's capacity depends on the law of the place where it was formed, while a partnership or other unincorporated group can sue or be sued under its own name. Minors and people who cannot manage their own affairs need a guardian, conservator, or similar representative to act for them in court, and if none exists, the court must appoint a guardian ad litem or next friend to protect them. Rule 17 also allows a lawsuit against a defendant whose real name is unknown, using a placeholder name until the truth comes out, and lets a public officer be sued by title rather than by name.

Frequently Asked Questions

What does real party in interest mean?

It means the person who holds the legal right being sued on must be the one bringing the case, rather than someone with no direct stake in the outcome.

Can a trustee sue in the trust's name instead of the beneficiaries' names?

Yes. Trustees, executors, administrators, guardians, bailees, and similar representatives can sue in their own names without joining the people they represent.

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

The court cannot dismiss the case for that reason alone. It must give the real party in interest reasonable time to ratify the lawsuit, join it, or be substituted in, after which the case continues as if it had started that way.

Who can sue on behalf of a child or a person who cannot manage their own affairs?

A general guardian, conservator, committee, or similar fiduciary can sue or defend on their behalf. If no representative exists or one fails to act, the court must appoint a guardian ad litem or allow a next friend to step in.

Can I sue someone whose real name I do not know yet?

Yes. You can name the defendant using a description and the words real name unknown in the summons, then amend the pleading once the true name is discovered, as long as a copy is served on the defendant personally.

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

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