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 Georgia, the right to intervene in a lawsuit is governed by the Georgia Civil Practice Act. Under O.C.G.A. § 9-11-24, a person or entity may intervene in an ongoing lawsuit if they have an interest in the matter being litigated. The statute allows for intervention as of right when the intervenor claims an interest relating to the property or transaction that is the subject of the action, and they are so situated that disposing of the action may as a practical matter impair or impede their ability to protect that interest. Intervention is also permitted when the intervenor's claim or defense and the main action have a question of law or fact in common. In Georgia, the intervenor must file a timely motion and serve a copy of the pleading on all parties. The court has the discretion to permit or deny intervention, but it may be considered an abuse of discretion to strike an intervention if the intervenor meets the criteria mentioned in the topic description, the intervention does not overly complicate the case, and the intervention is necessary to protect the intervenor's interests. If a party opposes the intervention, they bear the burden of challenging it by filing a motion to strike.