What is an intervention?

In U.S. civil cases, “intervention” is a procedure that lets a person who is not a party to a particular case join the case in order to protect her own interests.

Although personal injury and other torts cases are thought of as involving only one injured person, the plaintiff, and one person who may be liable, the defendant, the truth is that many cases involve more than one plaintiff or defendant. Like cross-claims, counter-claims, and impleader, intervention is a type of joinder used to add parties to cases when doing so will allow the court to resolve the dispute more efficiently and/or more fairly.

When an outside person wishes to intervene in a case, she must file a motion to intervene with the court. The motion explains what the person’s interests are in the case and the legal basis that supports her request to be allowed to join the action. If she is added, she is known as the “intervenor.”

Intervention may be “as of right” or “permissive.” In order to show that intervention should be “as of right,” the intervenor must show that:

• the intervenor has an interest related to the property or transaction involved in the case,
• the intervenor cannot adequately protect her own interests unless she is included in the case, and
• none of the parties already in the case can adequately represent the intervenor’s interests.

The intervenor’s “interest” in the outcome of the case does not have to be a financial interest, though many petitions to intervene in a case are based on money issues. A person may intervene in a case to protect a Constitutional right or other interest as well.

Often, a person seeking to intervene will argue that none of the parties can represent her interests because of fraud, collusion, or other wrongdoing that pits the intervenor against one or both of the parties in the case. Another common reason for intervening is that the legal arguments that will best serve the parties in the case are not the same as the legal arguments that will best protect the intervenor.

When an intervention is not “as of right,” courts have broad powers to decide whether or not to allow the intervention. When arguing for a “permissive” intervention, the person intervening must show that either:

• a statute creates a conditional right to intervene, or
• the intervenor’s claim or defense shares a common question of law or fact with the issues in the case.

Unlike counter-claimants or third-party claimants, who are given some “wiggle room” to bring up issues that are indirectly related to the original case, intervenors are expected to stick to issues that are closely and directly related to the original case. The purpose of this rule is to protect the original parties from wasted time, money, and energy caused by intervenors who want to argue about something other than the issues in the original case. Intervenors who want to argue about tangential issues may file their own cases if they wish.

Both a “permissive” intervention and an intervention “as of right” may still be denied by a court if the motion to intervene is filed so late in the process that allowing the intervenor to come in would do more harm than good. Also, an intervention will be prohibited, even if it is “as of right,” if the court does not have subject-matter jurisdiction over the intervenor’s issues.