A third person having an interest therein may intervene in a pending action to enforce a right related to or connected with the object of the pending action against one or more of the parties thereto by:
Art. 1091.Third Person May Intervene
Book II. Ordinary Proceedings · Title I. Pleading · Chapter 6. Incidental Actions · Amendment history unavailable · Last verified July 30, 2026
In one sentenceArticle 1091 lets a third person with an interest in a pending action intervene to enforce a right related to or connected with the object of the suit, by joining the plaintiff, uniting with the defendant, or opposing both parties.
Full Text of Art. 1091
(1) Joining with plaintiff in demanding the same or similar relief against the defendant;
(2) Uniting with defendant in resisting the plaintiff's demand; or
(3) Opposing both plaintiff and defendant.
Plain-English Summary
Intervention is Louisiana's device for letting an outsider step into a lawsuit that's already underway. Unlike reconvention, cross-claims, and third-party demands — all of which are set in motion by someone already a party to the case — intervention is initiated by the outsider. Article 1091 lets a third person with an interest join a pending action to enforce a right related to or connected with what the suit is about.
The article lays out three ways to intervene, each reflecting a different relationship to the existing dispute. The intervener can join the plaintiff, demanding the same or similar relief against the defendant. The intervener can unite with the defendant, resisting the plaintiff's demand. Or the intervener can oppose both sides, asserting a position that neither the plaintiff nor the defendant is advancing.
What ties all three together is the intervener's own stake in the outcome. Louisiana doesn't require the third person to wait for a separate lawsuit, or to be formally joined by one of the existing parties, when their own interest connects directly to the case already before the court.
Frequently Asked Questions
What is intervention under Louisiana law?
It's the device that lets a third person with an interest in a pending lawsuit join that suit to enforce a right related to or connected with what the suit is about, rather than filing a separate case.
Who initiates an intervention, an existing party or the outsider?
The outsider — the third person seeking to join the case files the petition of intervention. That's different from reconvention, cross-claims, and third-party demands, which existing parties initiate.
What are the three ways a third person can intervene under Article 1091?
Joining with the plaintiff to seek similar relief against the defendant, uniting with the defendant to resist the plaintiff's demand, or opposing both the plaintiff and the defendant.
Does a third person need permission from the existing parties to intervene?
No. Article 1091 lets a third person with the required interest intervene on their own initiative, though the intervention petition still has to be served on the parties.
Source & verification. Article text is reproduced verbatim from
the Louisiana Code of Civil Procedure (legis.la.gov). Enacted by the Louisiana Legislature.
Last verified July 30, 2026.
· Official source
Also known as: intervention louisiana civil procedurethird party joining a lawsuit louisianahow to intervene in a pending casetypes of intervention louisiana