Last amended July 1, 1999 · Last verified July 1, 2026
In one sentenceRule 24 lets someone who is not yet a party join a pending lawsuit -- either as of right, when a statute or a threatened interest demands it, or with the court's permission, when the applicant's claim shares a common question with the case -- by timely motion accompanied by the pleading the applicant wants to file.
Upon timely application anyone shall be permitted to intervene in an action: (1) when a statute of this state confers an unconditional right to intervene; or (2) when the applicant claims an interest relating to the property or transaction that is the subject of the action and the applicant is so situated that the disposition of the action may as a practical matter impair or impede the applicant’s ability to protect that interest, unless the applicant's interest is adequately represented by existing parties.
Upon timely application anyone may be permitted to intervene in an action: (1) when a statute of this state confers a conditional right to intervene; or (2) when an applicant's claim or defense and the main action have a question of law or fact in common. When a party to an action relies for ground of claim or defense upon any statute or executive order administered by a federal or state governmental officer or agency or upon any regulation, order, requirement or agreement issued or made pursuant to the statute or executive order, the officer or agency upon timely application may be permitted to intervene in the action. In exercising its discretion the court shall consider whether the intervention will unduly delay or prejudice the adjudication of the rights of the original parties.
A person desiring to intervene shall serve a motion to intervene upon the parties as provided in Civ.R. 5. The motion and any supporting memorandum shall state the grounds for intervention and shall be accompanied by a pleading, as defined in Civ.R. 7(A), setting forth the claim or defense for which intervention is sought. The same procedure shall be followed when a statute of this state gives a right to intervene.
Amendment History
Effective Date: July 1, 1970
Amended: July 1, 1999
Staff Note (July 1, 1999 Amendment)
Rule 24(A) Intervention of right
Masculine references were made gender-neutral; there were no substantive amendments to this division.
Rule 24(C) Procedure
The 1999 amendment was intended to clarify that the “pleading” to be filed with a motion to intervene requires more than just a memorandum in support of the motion to intervene. The Note following Form 17 in the Appendix of Forms was amended accordingly.
Plain-English Summary
Division (A) gives an outsider an unconditional right to intervene in two situations: when a state statute grants that right, or when the applicant claims an interest in the property or transaction at the heart of the case, and resolving the case without the applicant could as a practical matter impair the applicant’s ability to protect that interest, unless an existing party already adequately represents it. In either situation, the application must be timely; the longer someone waits after learning of the case, the harder it becomes to intervene.
Division (B) allows permissive intervention when a statute grants a conditional right to intervene, or when the applicant’s claim or defense shares a question of law or fact with the main action. It also lets a government officer or agency intervene when a party’s claim or defense rests on a statute, executive order, or regulation that officer or agency administers. Because permissive intervention is discretionary, the court must weigh whether allowing it will unduly delay or prejudice the rights of the parties already in the case.
Division (C) sets the mechanics for either kind of intervention: the applicant serves a motion to intervene on the existing parties, the motion and any supporting memorandum must state the grounds for intervening, and the motion must be accompanied by a pleading — a complaint or answer — that sets out the claim or defense for which intervention is sought. The same procedure applies when a statute independently gives someone a right to intervene.
Frequently Asked Questions
What is the difference between intervention of right and permissive intervention?
Intervention of right under Rule 24(A) must be allowed when a statute grants it or when the applicant's protectable interest could be impaired by the case going forward without them. Permissive intervention under Rule 24(B) is left to the court's discretion, typically because the applicant's claim or defense shares a common question with the case.
What has to accompany a motion to intervene?
Rule 24(C) requires the motion to state the grounds for intervening and to be accompanied by a pleading — a complaint or answer — setting out the claim or defense the applicant wants to assert.
Can a court deny intervention even if the applicant otherwise qualifies?
For permissive intervention, yes — the court must consider whether allowing it will unduly delay or prejudice the rights of the existing parties. Intervention of right, by contrast, must be allowed once its conditions are met and the application is timely.
Source & verification. The rule text, Effective Date, Amended dates, and Staff Notes are reproduced verbatim from the
official Ohio Rules of Civil Procedure (Ohio R. Civ. P. 24). Prescribed by the Supreme Court of Ohio (Ohio Constitution, Art. IV, § 5(B)). The plain-English summary is original and written by us. Last verified July 1, 2026. ·
Official source
Also known as:intervention of rightpermissive interventionmotion to intervene