Rule 24. Intervention.

(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 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 motions shall state the grounds therefor and shall be accompanied by a pleading setting forth the claim or defense for which intervention is sought.

(d) Constitutionality of statutes and ordinances.

(d)(1) If a party challenges the constitutionality of a statute in an action in which the Attorney General has not appeared, the party raising the question of constitutionality shall notify the Attorney General of such fact. The court shall permit the state to be heard upon timely application.

(d)(2) If a party challenges the constitutionality of a county or municipal ordinance in an action in which the county or municipal attorney has not appeared, the party raising the question of constitutionality shall notify the county or municipal attorney of such fact. The court shall permit the county or municipality to be heard upon timely application.

(d)(3) Failure of a party to provide notice as required by this rule is not a waiver of any constitutional challenge otherwise timely asserted.