Rule 212.Intervention
Part II. Pleadings · Last amended July 1, 2021 · Last verified September 4, 2026
Full Text of Rule 212
Rule History
(Adopted March 29, 2021, effective July 1, 2021.)
Plain-English Summary
Rule 212 lets someone who is not a party join a case on their own initiative.
Of right
On timely motion the court must permit anyone to intervene who has an unconditional right under an Idaho statute, or who claims an interest in the property or transaction that is the subject of the action and is so situated that disposing of the action may as a practical matter impair or impede their ability to protect it — unless the existing parties adequately represent that interest.
Permissive
On timely motion the court may permit anyone with a conditional statutory right, or with a claim or defense sharing a common question of law or fact with the main action. A federal or state officer or agency may intervene where a claim or defense rests on a statute or executive order it administers, or a regulation or order made under one. In exercising discretion the court must consider whether the intervention will unduly delay or prejudice the original parties' rights.
Procedure
The motion is filed and served under Rule 205, must state the grounds, and must be accompanied by a pleading setting out the claim or defense for which intervention is sought.
Health and Welfare
A motion by the Idaho Department of Health and Welfare to obtain, enforce or modify a child support order may be granted without hearing — subject to a later hearing on an objecting party's motion — and service of the motion and any order may be by mail to the last known address. Support enforcement does not wait on a hearing it may never need.
De facto custodian
A request for de facto custodian status requires an existing Idaho custody order or a pending Idaho custody proceeding about that child — and expressly does not include actions under title 16 of the Idaho Code. The motion for permissive intervention is served under Rule 203 in a pending custody proceeding, or under Rule 204 — as original process — if the custody proceeding is closed, with a notice of hearing under Rule 501(a)(3).
If intervention is granted, a petition for de facto custodian status and custody may be filed, served and adjudicated substantially as an original action, with the notice of hearing directing a written response within 21 days.
Frequently Asked Questions
When must the court let someone intervene?
Rule 212(a) requires it on timely motion where an Idaho statute gives an unconditional right, or where the movant claims an interest in the property or transaction and disposing of the action may as a practical matter impair or impede their ability to protect it, unless existing parties adequately represent that interest.
What must accompany a motion to intervene?
Rule 212(c) requires the motion to state the grounds for intervention and to be accompanied by a pleading that sets out the claim or defense for which intervention is sought.
Does the Department of Health and Welfare need a hearing to intervene?
No. Rule 212(d) allows a motion by the Idaho Department of Health and Welfare to obtain, enforce or modify a child support order to be granted without hearing, subject to a later hearing upon a motion by an objecting party.
How does a de facto custodian join a case?
Rule 212(e)(1) requires an existing Idaho custody order or a pending Idaho custody proceeding, with the motion for permissive intervention served under Rule 203 in a pending proceeding or under Rule 204 if the custody proceeding is closed.
What happens after de facto custodian intervention is granted?
Rule 212(e)(2) allows a petition for de facto custodian status and custody to be filed, served and adjudicated substantially as an original action, with the notice of hearing directing a written response within 21 days.