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 Kansas, the rules regarding intervention in a lawsuit are governed by the Kansas Code of Civil Procedure. A person or entity, known as an intervenor, may seek to become a party to a lawsuit by filing a motion to intervene, typically before the court has entered a judgment. The intervenor does not need to obtain permission from the court to intervene, but the intervention can be challenged by an existing party through a motion to strike. The right to intervene is generally granted if the intervenor could have initiated the same lawsuit or would have a defense against the lawsuit if it were brought against them. The court may strike an intervention if it fails to meet certain criteria, such as not complicating the case with too many issues and being necessary to protect the intervenor's interests. A trial court's decision to strike an intervention can be considered an abuse of discretion if the intervenor meets the criteria for intervention, the case is not unduly complicated by the intervention, and the intervention is essential to protect the intervenor's interests.