Group IV: Parties · Last amended March 1, 2017 · Last verified July 14, 2026
In one sentenceRule 24 governs when an outside person or entity may join a pending lawsuit, either as a matter of right or with the court's permission.
(a)Intervention of Right. — On timely motion, the court must permit anyone to intervene who:
(1)is given an unconditional right to intervene by statute; or
(2)claims an interest relating to the property or transaction that is the subject of the action, and is so situated that disposing of the action may as a practical matter impair or impede the movant’s ability to protect its interest, unless existing parties adequately represent that interest.
(1)In General. — On timely motion, the court may permit anyone to intervene who:
(A)is given a conditional right to intervene by statute; or
(B)has a claim or defense that shares with the main action a common question of law or fact.
(2)By a Government Officer or Agency. — On timely motion, the court may permit a federal or state governmental officer or agency to intervene if a party’s claim or defense is based on:
(A)a statute or executive order administered by the officer or agency; or
(B)any regulation, order, requirement, or agreement issued or made under the statute or executive order.
(3)Delay or Prejudice. — In exercising its discretion, the court must consider whether the intervention will unduly delay or prejudice the adjudication of the original parties’ rights.
(c)Notice and Pleading Required. — A motion to intervene must be served on the parties as provided in Rule 5. The motion must state the grounds for intervention and be accompanied by a pleading that sets out the claim or defense for which intervention is sought.
Amendment History
Added February 2, 2017, effective March 1, 2017.
Plain-English Summary
Litigation sometimes affects people who were never named as parties. Rule 24 gives those people a way in. Intervention of right applies when a statute gives an unconditional right to join, or when someone has a real stake in the property or transaction at issue and the existing parties will not adequately protect that interest — meaning the outcome could practically hurt the outsider’s interests even though they were never part of the case. When those conditions are met and the request is timely, the court must let the person in.
Permissive intervention works differently: the court has discretion, not an obligation, to let someone join. That discretion covers people with a claim or defense that shares a common question of law or fact with the pending case, as well as government officers or agencies whose regulatory interests connect to a party’s claim or defense. Either way, the court weighs whether adding a new party will unduly delay the case or prejudice the rights of the people already litigating it. Anyone seeking to intervene must serve a motion on the existing parties explaining the grounds for joining and attach a pleading laying out the claim or defense they intend to bring.
Frequently Asked Questions
What is the difference between intervention of right and permissive intervention?
Intervention of right means the court must let the person join once the conditions are satisfied — typically an unconditional statutory right, or a practical impairment of the person's interest that existing parties won't adequately protect. Permissive intervention leaves the decision to the court's discretion, usually because the newcomer's claim or defense shares a common question with the case.
Can a government agency intervene in a private lawsuit?
Yes, on a timely motion, if a party's claim or defense rests on a statute or executive order the agency administers, or on a regulation, order, or agreement issued under that statute or order.
What happens if someone waits too long to move to intervene?
Timeliness is a threshold requirement for both types of intervention. A court can deny even an otherwise-qualifying request if it comes too late, particularly if letting the newcomer in at that point would unduly delay the case or prejudice the existing parties.
What must a motion to intervene include?
It must be served on the existing parties, state the grounds for intervention, and come with a pleading — such as a proposed complaint or answer — that lays out the claim or defense the intervenor wants to raise.
Does having an interest in the outcome automatically entitle someone to intervene?
No. For intervention of right based on an interest in the property or transaction, the person also has to show that disposing of the case could impair that interest as a practical matter, and that the existing parties are not already protecting it adequately.
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
Also known as:intervening in a lawsuitjoining an existing caseintervention of rightpermissive intervention rulethird party joining a case