(a) Real party in interest. Every action shall be prosecuted in the name of the real party in interest. An executor, administrator, guardian, bailee, trustee of an express trust, a party with whom or in whose name a contract has been made for the benefit of another, or a party authorized by statute may sue in its own name without joining with it the party for whose benefit the action is brought. No action shall be dismissed on the ground that it is not prosecuted in the name of the real party in interest until a reasonable time has been allowed after objection for ratification of commencement of the action by, or joinder or substitution of, the real party in interest; and such ratification, joinder, or substitution shall have the same effect as if the action had been commenced in the name of the real party in interest.
Rule 17.Parties Plaintiff and Defendant; Capacity.
Last amended January 1, 2000 · Last verified July 3, 2026
In one sentenceRule 17 requires a lawsuit to be brought in the name of the real party in interest, sets out who may sue on behalf of an infant or incompetent person, and lets a plaintiff sue an unidentified defendant under a fictitious name until the defendant's true identity can be discovered.
Full Text of Rule 17
(b) Reserved.
(c) Infants or incompetent persons. Whenever an infant or incompetent person has a guardian, whe- ther appointed as to that person or property, such guardian appointed as to property, or if no guardian has been appointed as to property, then such guardian appointed as to that person, may sue or defend on behalf of the infant or incompetent person. If an infant or incompetent person does not have a duly appointed guardian that person may sue by that person's next friend or by a guardian ad litem. The court shall appoint a guardian ad litem for an infant or incompetent person not otherwise represented in an action or shall make such other order as it deems proper for the protection of the infant or incompetent person.
(d) Unidentified defendant.
(1) When it shall be necessary or proper to make a person a party defendant and the party desiring the inclusion of the person as a party defendant has been unable to ascertain the identity of a defendant, the party desiring the inclusion of the person as a party defendant shall in accordance with the criteria of Rule 11 of these rules set forth in a pleading the person's interest in the action, so much of the identity as is known (and if unknown, a fictitious name shall be used), and shall set forth with specificity all actions already undertaken in a diligent and good-faith effort to ascertain the person's full name and identity.
(2) Subject to HRS section 657-22, the person intended shall thereupon be considered a party defendant to the action, as having notice of the institution of the action against that person, and as sufficiently described for all purposes, including services of process, and the action shall proceed against that person.
(3) Any party may, by motion for certification, make the name or identity of the party defendant known to the court within a reasonable time after the moving party knew or should have known the name or identity of the party defendant. The motion shall be supported by affidavit setting forth all facts substantiating the movant's claim that the naming or identification has been made in good faith and with due diligence. When the naming or identification is made by a plaintiff, it shall be made prior to the filing of the pretrial statement by that plaintiff, or within such additional time as the court may allow. The court shall freely grant reasonable extensions of the time in which to name or identify the party defendant to any party exercising due diligence in attempting to ascertain the party defendant's name or identity.
(4) When a party defendant has been named or identified in accordance with this rule, the court shall so certify and may make any order that justice requires to protect any party from undue burden and expense in any further proceedings involving the party defendant.
(5) A party defendant who has been named or identified in accordance with this rule may have dismissal of one or more claims against the defendant if the defendant shows in a timely manner that the delay in naming or identifying that defendant has caused that defendant substantial prejudice and if the interests of justice so require.
Amendment History
Amended May 15, 1972, effective July 1, 1972
further amended July 10, 1984, effective July 10, 1984
further amended July 26, 1990, effective September 1, 1990
further amended December 7, 1999, effective January 1, 2000
Plain-English Summary
Rule 17 requires every action to be prosecuted in the name of the real party in interest, the person who holds the right being sued on, though an executor, administrator, guardian, bailee, trustee of an express trust, a contracting party suing for another's benefit, or someone authorized by statute may sue in their own name without joining the person they represent. A case isn't dismissed for suing in the wrong name until the real party in interest has had a reasonable chance to ratify, join, or be substituted into the action, and doing so counts as if the suit had been properly brought from the start. An infant or incompetent person may sue or defend through a guardian, or, lacking one, through a next friend or a court-appointed guardian ad litem.
Rule 17(d) also lets a plaintiff who can't identify a defendant despite a diligent, good-faith effort name that defendant fictitiously, describing what is known about the person's interest in the case and the efforts already made to learn their identity. The unidentified defendant is treated as a party with notice of the suit from the start, and the plaintiff may later move to substitute the defendant's real name once it becomes known, supported by an affidavit of diligence; the court can protect the newly named defendant from undue burden, or dismiss claims against a defendant identified too late if the delay caused substantial prejudice and justice requires it.
Frequently Asked Questions
Who counts as the "real party in interest" under Rule 17?
The person who holds the substantive right being sued on; the rule requires every action to be prosecuted in that person's name, though certain representatives like executors, guardians, and trustees may sue in their own name instead.
Can a plaintiff sue a defendant whose identity is unknown?
Yes. Rule 17(d) lets a plaintiff who has made a diligent, good-faith effort to identify a defendant proceed against that defendant fictitiously, and later move to substitute the defendant's real name once it is discovered.
Who can sue or defend on behalf of a child or an incompetent person?
Rule 17(c) allows a duly appointed guardian to sue or defend on that person's behalf, or, if there is no guardian, a next friend or a guardian ad litem the court appoints.
Source & verification. The rule text and History are reproduced verbatim from the
official Hawaii Rules of Civil Procedure (Haw. R. Civ. P. 17). Prescribed by the Supreme Court of Hawaii (Haw. Rev. Stat. § 602-11; Haw. Const. art. VI, § 7). The plain-English summary is original and written by us. Last verified July 3, 2026. ·
Official source
Also known as: real party in interestsuing an unidentified defendantguardian ad litemnext friend