What Is Intervention in Federal Court?

A federal lawsuit does not always involve only the people or organizations that originally filed the case. Sometimes, another person, business, organization, or government entity has a legal interest in the outcome and wants to become part of the case.

This process is called intervention.

In federal court, intervention is generally governed by Federal Rule of Civil Procedure 24. It provides a way for a third party who was not originally named as a plaintiff or defendant to ask the court to join the existing lawsuit.

Intervention can be important because a court's decision in an existing case may affect someone who is not currently a party. Rather than remaining outside the lawsuit, that person may ask the court for permission to participate and protect their interests.

What Does Intervention Mean?

In simple terms, intervention means that a third party asks to enter an existing lawsuit.

For example, imagine that two companies are involved in a federal lawsuit concerning ownership of a piece of property. A third company claims that it has a legal interest in that same property. If the lawsuit is decided without the third company participating, its ability to protect its interest could potentially be affected.

The third company may therefore file a motion to intervene.

The person or organization seeking to enter the lawsuit is called an intervenor.

An intervenor may seek to participate on the side of the plaintiff, on the side of the defendant, or in another position allowed by the court and applicable law.

Federal Rule of Civil Procedure 24

Federal Rule of Civil Procedure 24 provides two primary forms of intervention:

1. Intervention of right

2. Permissive intervention

The distinction matters because the legal standard is different for each.

1. Intervention of Right

Intervention of right applies when the law gives the third party a right to participate in the case.

Under Rule 24(a), the court must permit intervention, on a timely motion, when either of the specified circumstances exists.

The first situation is when a federal statute gives the person an unconditional right to intervene.

The second situation generally involves a person who claims an interest related to the property or transaction involved in the lawsuit and is positioned so that resolving the case could practically impair or impede the person's ability to protect that interest, unless the existing parties adequately represent the interest.

In practical terms, the court considers whether the person seeking intervention has a significant interest connected to the lawsuit and whether the existing case could affect that interest.

Example of intervention of right

Suppose a federal lawsuit concerns a government decision affecting a particular property, and a third party claims a direct legal interest in that property.

If the outcome of the lawsuit could substantially affect the third party's ability to protect that interest, the third party may seek intervention under Rule 24(a)(2).

The court must apply the requirements of Rule 24 rather than simply allowing someone to join because they are interested in the dispute.

2. Permissive Intervention

Permissive intervention is different.

Under Rule 24(b), a federal court may permit a third party to intervene when the third party has a claim or defense that shares a common question of law or fact with the main lawsuit.

A federal statute can also provide a conditional right to intervene. Rule 24(b) separately addresses certain requests by governmental officers or agencies when the circumstances described in the rule are present.

Unlike intervention of right, permissive intervention involves judicial discretion.

The court must consider whether allowing the third party to enter the case would cause undue delay or prejudice to the rights of the original parties.

Example of permissive intervention

Imagine that a federal lawsuit involves a particular federal regulation. A government agency responsible for administering that regulation may seek permission to intervene if the requirements of Rule 24(b) are satisfied.

The court then considers the applicable legal requirements and whether intervention would unnecessarily delay or prejudice the existing litigation.

Who Can Intervene in a Federal Case?

Intervention is not limited to individuals.

Depending on the circumstances and applicable law, an intervenor can be a:

• Individual

• Business

• Organization

• Government agency

• Federal or state governmental officer

• Other entity with a legally recognized interest

However, simply having an opinion about a lawsuit usually is not enough. The person seeking intervention must satisfy the requirements of Rule 24 or another applicable statute.

How Do You Ask a Federal Court to Intervene?

A person who wants to intervene generally files a motion to intervene with the federal court handling the case.

Rule 24(c) requires the motion to be served on the existing parties. The motion must explain the grounds for intervention and must be accompanied by a pleading setting out the claim or defense for which intervention is sought.

The exact filing requirements can also depend on the federal district court's local rules and the circumstances of the particular case.

This means a person should not assume that simply filing a document saying "I want to join the case" will be sufficient.

Why Is Timing Important?

Timing can be extremely important in an intervention request.

Rule 24 requires a motion to intervene to be timely. The rule does not provide one universal number of days that applies to every case. Whether a motion is timely can depend on the circumstances of the litigation and the applicable law.

Waiting until very late in a case can create additional problems, particularly when intervention could disrupt proceedings that are already substantially advanced.

For that reason, someone who believes their legal interests may be affected should examine the possibility of intervention as early as reasonably possible.

Does Intervention Make Someone a Full Party?

Intervention can allow a third party to participate in the litigation, but the precise scope of that participation can depend on the type of intervention, the court's order, the claims and defenses involved, and other applicable law.

The Supreme Court has recognized the distinction between intervention of right and permissive intervention under Rule 24.

A person should therefore carefully review the court's order granting intervention to understand what claims, defenses, or participation rights have actually been permitted.

Intervention vs. Joinder

Intervention and joinder are related but are not the same thing.

Joinder generally concerns bringing additional parties or claims into a lawsuit under applicable procedural rules.

Intervention involves a person or entity that was not originally a party asking to enter an already existing lawsuit.

Federal Rule of Civil Procedure 24 specifically addresses intervention, while other Federal Rules address different forms of joinder.

Understanding this distinction is important when determining which procedural rule applies to a particular federal case.

Intervention vs. Amicus Curiae

Intervention should also not be confused with filing an amicus curiae brief.

An intervenor becomes a participant in the litigation, subject to the scope of the court's order and applicable procedural rules.

An amicus curiae, often called a "friend of the court," generally provides information, arguments, or expertise to assist the court but does not become a party simply by filing an amicus brief.

The two procedures therefore serve different purposes.

Special Intervention When a Law's Constitutionality Is Challenged

Federal law contains a specific provision concerning intervention when the constitutionality of a federal or state statute is challenged.

Under 28 U.S.C. § 2403, when the constitutionality of an Act of Congress affecting the public interest is questioned in a federal proceeding and the United States is not already a party, the court must certify that fact to the Attorney General and permit the United States to intervene for the purposes described by the statute.

A similar provision applies when the constitutionality of a state statute affecting the public interest is questioned and the state or its relevant agency or officer is not already a party.

Federal Rule of Civil Procedure 5.1 also establishes procedures for notifying the appropriate government authorities when the constitutionality of a statute is challenged.

This is a specialized form of intervention and should not be confused with ordinary requests to intervene under Rule 24.

What Happens After a Motion to Intervene Is Filed?

The existing parties generally have an opportunity to respond to the motion.

The federal judge then determines whether the requirements for intervention have been satisfied.

For intervention of right, the court applies Rule 24(a).

For permissive intervention, the court considers Rule 24(b), including whether the proposed intervention shares a common question of law or fact with the existing case and whether intervention would cause undue delay or prejudice.

The court may also consider other procedural and case-specific issues.

If intervention is granted, the intervenor participates according to the court's order and the applicable rules.

If intervention is denied, the third party generally remains outside the lawsuit, although other legal options may sometimes exist depending on the circumstances.

Can Intervention Affect the Existing Lawsuit?

Yes.

Allowing another party into an existing federal lawsuit can expand the issues that the court must consider. The intervenor may present claims or defenses within the scope of the intervention and participate in the litigation as permitted by the court.

That is one reason Rule 24 requires courts to consider issues such as delay and prejudice, particularly when permissive intervention is requested.

Intervention is therefore not simply a way for someone to express an opinion about a case. It is a formal procedural mechanism that can give a qualifying third party a role in the litigation.

Frequently Asked Questions

Is intervention automatic in federal court?

No. The person seeking intervention must satisfy the requirements of the applicable rule or statute. Intervention of right and permissive intervention have different standards.

Does an intervenor have to be a plaintiff?

No. Depending on the circumstances, an intervenor may seek to participate on the plaintiff's side, the defendant's side, or in another position permitted by law.

Can a business intervene in a federal lawsuit?

Potentially, yes. A business can seek intervention if it satisfies the applicable requirements of Rule 24 or another federal statute.

Does an intervenor need to file a motion?

Generally, yes. Rule 24 requires a timely motion and specifies additional requirements concerning service, the grounds for intervention, and the pleading accompanying the motion.

Is there a deadline for intervention?

There is a timeliness requirement, but Rule 24 does not establish one universal deadline for every case. The circumstances of the particular litigation matter.

Can a person intervene simply because they disagree with the lawsuit?

Usually, disagreement alone is not enough. The person must satisfy the applicable requirements for intervention.

Final Takeaway

Intervention is a federal court procedure that allows a qualifying third party to enter an existing lawsuit.

Under Federal Rule of Civil Procedure 24, intervention generally falls into two categories: intervention of right and permissive intervention. Intervention of right can require the court to allow participation when the rule's requirements are satisfied, while permissive intervention gives the court discretion when the applicable requirements are met.

Because intervention can affect a person's legal rights and the course of an existing lawsuit, timing and procedural requirements matter. Anyone considering intervention should review the federal rules, the local rules of the particular district court, and the facts of the case before filing.

Sources

• U.S. Courts — Federal Rules of Civil Procedure, Rule 24: Intervention.

• Cornell Law School Legal Information Institute — Federal Rule of Civil Procedure 24.

• Cornell Law School Legal Information Institute — Intervention / Wex.

• 28 U.S.C. § 2403 — Intervention by United States or a State; constitutional question.

• Federal Rule of Civil Procedure 5.1 — Constitutional Challenge to a Statute.

• U.S. Supreme Court — Stringfellow v. Concerned Neighbors in Action, 480 U.S. 370 (1987).

Legal Disclaimer

This article is provided for general informational and educational purposes only. It is not legal advice and does not create an attorney-client relationship. Federal procedural requirements can vary depending on the type of case, federal district, local rules, and individual circumstances. If you are considering filing a motion to intervene or believe a federal lawsuit may affect your legal rights, consider consulting a qualified attorney about your specific situation.