Duhaime's Law Dictionary

Intervener Definition:

One who is given standing in litigation even though they were not originally a party.

A person who has not been named as plaintiff or defendant to litigation, or in any other has been added as a party, and who seeks to defend interests which he or she reasonably fears may be compromised or interfered with, by the result of litigation in the event of his or her silence and lack of standing before the court.

In Pitzel, Justice Hamilton of the Manitoba Court of Queen's Bench adopted these words:

"[O]ne who intervenes in a suit to which he was not originally a party"

Contrary to a third-party, an intervener generally seeks locus standi - standing in litigation - to be heard.

In Barnard, Justice Flanagan of the Appellate Court of Indiana wrote:

"An intervener is ... one who is seeking to become a party to a suit for the purpose of protecting an interest of his own which neither the plaintiff nor the defendant is interested in protecting. Strictly speaking, he is not in any sense a party to the suit until permission to intervene is granted."

The traditional common law approach was to disallow intervenors; the refrain being that only parties with a triable interest in the actual issues raised in the pleadings have a right to be heard. The Court rules in many jurisdictions provide for intervenors. In the absence of such rules, there is an argument that, as stated in the 2003 Canadian treatise Civil Procedure Encyclopedia:

"There is an inherent power in the court to allow interventions."

In Fishing Vessel Owners', Justice Addy all but declared that the authority to add an intervenor to an existing litigation, though neither plaintiff nor defendant, and in the absence of a triable issue in his/her regard in the pleadings, is a authority the court has because of its inherent jurisdiction. In allowing an application by an individual to be added as intervenor, Addy wrote:

"There exists no prohibition in any statute or in our rules against allowing an intervenor to be heard. Every tribunal has the fundamental power to control its own procedure in order to ensure that justice is done."

Also occasionally presented as intervenor.

French: intervenant.


  • Barnard v Kruzan 44 N.E. 2d 233 (1942)
  • Fishing Vessel Owners' Assn. of British Columbia v. Canada, 1 C.P.C. (2d) 312, 57 N.R. 376 (Federal Court of Canada, Appeal Division, 1985)
  • Pitzel v. Children's Aid Society of Winnipeg, [1984] 5 W.W.R. 474, 45 C.P.C. 313, 29 Man. R. (2d) 297, [1984] 4 C.N.L.R. 41

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