A person or entity who is not a party to a lawsuit generally may intervene in the lawsuit and become a party to it by filing a plea in intervention prior to the entry of the court’s judgment—provided the court does not reject (strike) the intervention. An intervenor is not required to secure the court’s permission to intervene, and the party who opposed the intervention has the burden to challenge it by filing a motion to strike.

A person or entity has a right to intervene if the intervenor could have brought the same lawsuit, or any part of it in his own name—or, if the action had been brought against him, he would be able to defeat the lawsuit, or some part of it.

A trial court abuses its discretion by striking an intervention if (1) the intervenor meets the above test, (2) the intervention will not complicate the case by an excessive multiplication of the issues, and (3) the intervention is almost essential to effectively protect the intervenor’s interest.

In Wyoming, the rules regarding intervention in a lawsuit are similar to those described. A person or entity, not originally a party to a lawsuit, may intervene by filing a plea in intervention before the court renders a judgment. The court does not need to grant permission for this intervention; however, if the intervention is opposed, the opposing party must file a motion to strike to challenge it. The right to intervene is typically granted if the potential intervenor has a significant interest in the lawsuit, such that they could have initiated the same lawsuit themselves or would have a defense against it if they were named as a defendant. The court may only strike an intervention if it fails to meet the criteria of having a justifiable interest, if it unduly complicates the case, or if the intervention is not necessary to protect the intervenor's interests. If an intervention is struck despite meeting these conditions, it may be considered an abuse of discretion by the trial court. It's important to note that while these general principles apply, specific Wyoming statutes and rules of civil procedure would provide detailed guidance on intervention in that state.