Chapter IV: Parties · Not amended since adoption on record · Last verified July 14, 2026
In one sentenceRule 24 lets a person intervene in a pending action either as of right, when a statute grants that right or when the applicant's interest in the case would otherwise be impaired without adequate representation, or permissively, when the court allows it because the applicant's claim or defense shares a common question with the main action.
(a)Intervention of Right. Upon timely application, anyone shall be permitted to intervene in an action:
(1)when a statute confers an unconditional right to intervene; or
(2)when the applicant claims an interest relating to the property or transaction which is the subject of the action and he is so situated that the disposition of the action may as a practical matter impair or impede his ability to protect that interest, unless the applicant’s interest is adequately represented by existing parties.
(b)Permissive Intervention. Upon timely application anyone may be permitted to intervene in an action:
(1)when a statute 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.
(c)Procedure. A person desiring to intervene shall serve a motion to intervene upon the parties as provided in Rule 5. The motion shall state the grounds therefor and shall be accompanied by a pleading setting forth the claim or defense for which intervention is sought. The same procedure shall be followed when a statute gives a right to intervene.
(d)Intervention by the State. In any action (1) to restrain or enjoin the enforcement, operation, or execution of any statute of the State of Mississippi by restraining or enjoining the action of any officer of the State or any political subdivision thereof, or the action of any agency, board, or commission acting under state law, in which a claim is asserted that the statute under which the action sought to be restrained or enjoined is to be taken is unconstitutional, or (2) for declaratory relief brought pursuant to Rule 57 in which a declaration or adjudication of the unconstitutionality of any statute of the State of Mississippi is among the relief requested, the party asserting the unconstitutionality of the statute shall notify the Attorney General of the State of Mississippi within such time as to afford him an opportunity to intervene and argue the question of constitutionality.
Advisory Committee Notes
Rule 24 requires the court to balance the interests of the would-be intervenor against the burdens such intervention might pose on those already parties or on the judicial system’s economic and efficient disposition of the case. If one of the criteria for intervention as a matter of right is met and the would-be intervenor files a timely application for intervention, intervention shall be allowed. See Dare v. Stoke, 62 So. 3d 958, 959 (Miss. 2011). A trial court has discretion when ruling on a timely motion to permissively intervene and “may permissively grant or deny a motion to intervene, provided there is a common question of law or fact and the motion was timely filed.” See Madison HMA, Inc. v. St. Dominic-Jackson Mem’l Hosp., 35 So. 3d 1209, 1215 (Miss. 2010).
Applications to intervene as of right pursuant to Rule 24(a) or to permissively intervene pursuant to Rule 24(b) must be timely. The rule does not set out any specific time limits. Instead, trial courts are to weigh the following four factors when determining timeliness: “(1) the length of time during which the would-be intervenor actually knew or should have known of his interest in the case before he petitioned for leave to intervene; (2) the extent of the prejudice that the existing parties to the litigation may suffer as a result of the would-be intervenor’s failure to apply for intervention as soon as he actually knew or reasonably should have known of his interest in the case; (3) the extent of the prejudice that the would-be intervenor may suffer if his petition for leave to intervene is denied; and (4) the existence of unusual circumstances mitigating either for or against a determination that the application is timely.” See Hood ex rel. State Tobacco Litigation, 958 So. 2d 790, 806 (Miss. 2007). The determination of whether an application to intervene is timely is committed to the discretion of the trial court and will not be overturned on appeal absent an abuse of discretion.
Plain-English Summary
Rule 24 gives outsiders to a lawsuit a way in when the case affects them directly. Rule 24(a) covers intervention as of right: on timely application, anyone must be permitted to intervene when a statute gives an unconditional right to do so, or when the applicant claims an interest in the property or transaction at issue and resolving the case without them could, as a practical matter, impair or impede their ability to protect that interest — unless the existing parties already adequately represent it. Because intervention as of right is not discretionary once those conditions are met, timeliness is critical; courts weigh how long the applicant knew or should have known about their interest, the prejudice delay causes to the existing parties, the prejudice denial would cause the applicant, and any unusual circumstances bearing on the timing.
Rule 24(b) covers permissive intervention, which is left to the court's discretion. A person may be allowed to intervene when a statute confers a conditional right to do so, or when their claim or defense shares a common question of law or fact with the main action. The rule also lets a government officer or agency intervene when a party's claim or defense rests on a statute, executive order, or related regulation that the officer or agency administers, so long as the court considers whether the intervention would unduly delay or prejudice the existing parties' case.
Rule 24(c) sets the mechanics: a would-be intervenor serves a motion to intervene under Rule 5, states the grounds for intervention, and attaches a pleading setting out the claim or defense being asserted. Rule 24(d) adds a distinct notice requirement for constitutional challenges — when a party attacks the constitutionality of a Mississippi statute in a suit to restrain a state officer or in a declaratory judgment action under Rule 57, that party must notify the Attorney General in time to allow the state to intervene and argue the statute's constitutionality.
Frequently Asked Questions
What is the difference between intervention as of right and permissive intervention?
Intervention as of right under Rule 24(a) must be allowed when a statute confers an unconditional right or when the applicant's interest in the case would be impaired without adequate representation by the existing parties. Permissive intervention under Rule 24(b) is left to the court's discretion and applies when a statute confers a conditional right or when the applicant's claim or defense shares a common question of law or fact with the main action.
How quickly do I need to seek intervention?
The application must be timely, though Rule 24 does not fix a specific deadline. Courts weigh how long the applicant knew or should have known of their interest, the prejudice to existing parties from any delay, the prejudice to the applicant if intervention is denied, and any unusual circumstances affecting timeliness.
What does a motion to intervene have to include?
Rule 24(c) requires the motion to be served on the parties under Rule 5, to state the grounds for intervention, and to be accompanied by a pleading setting out the claim or defense the applicant wants to assert.
When does a case require notifying the Attorney General under Rule 24(d)?
When a party challenges the constitutionality of a Mississippi statute in a suit seeking to restrain a state officer's enforcement of it, or in a declaratory judgment action under Rule 57 that seeks a declaration the statute is unconstitutional, that party must notify the Attorney General in time to allow the state to intervene and argue the constitutionality question.
Can a government agency intervene in a private lawsuit under Rule 24?
Yes, when a party's claim or defense relies on a statute, executive order, or related regulation administered by that agency. The court considers whether the intervention would unduly delay or prejudice the existing parties before allowing it.
Source & verification. Rule text and Advisory Committee Notes are
reproduced verbatim from the Mississippi Rules of Civil Procedure, adopted by the
Supreme Court of Mississippi. Last verified July 14, 2026.
· Official source
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