Misjoinder of parties is not a ground for dismissing an action. On motion or on its own, the court may at any time, on just terms, add or drop a party. The court may also sever any claim against a party.
Rule 21.Misjoinder and nonjoinder of parties
Title IV: Parties · Last amended July 1, 2016 · Last verified July 14, 2026
In one sentenceRule 21 makes clear that joining the wrong parties never dooms a lawsuit outright, since the court can add, drop, or sever parties on its own or on motion at any point in the case.
Full Text of Rule 21
Amendment History
(Adopted March 1, 2016, effective July 1, 2016.)
Plain-English Summary
Rule 21 takes dismissal off the table when a case has the wrong mix of parties. Misjoinder, whether too many parties, the wrong parties, or parties who don't belong together, isn't itself a reason to throw a case out. Instead, the court has continuing authority to fix the problem directly, adding a party who should be there or dropping one who shouldn't, whenever the situation calls for it and on terms that are fair to everyone involved.
The rule also gives the court a way to untangle claims that got bundled together but don't belong in the same trial. On motion or on its own initiative, the court can sever a claim against a particular party into a separate proceeding, letting each piece of the dispute move at its own pace without holding up the rest of the case. This flexibility means a mistake in framing who's in or out of a lawsuit rarely has to be fatal.
Frequently Asked Questions
Does suing the wrong combination of parties get a case dismissed?
No. Misjoinder of parties is not by itself a ground for dismissing an action under Rule 21.
Can the court add a party on its own, without anyone asking?
Yes. The court can add or drop a party on motion or on its own, at any time, on just terms.
What does it mean to "sever" a claim under Rule 21?
It means splitting a claim against a particular party out of the existing case so it proceeds as its own separate matter.
Is there a deadline for fixing a misjoinder problem?
No. Rule 21 lets the court act at any time during the case.
How does Rule 21 relate to Rule 19's joinder requirements?
Rule 19 identifies who must be joined for a case to proceed on the merits. Rule 21 supplies the mechanism for adding or dropping parties and confirms that joinder problems aren't fatal to the case.
Source & verification. Rule text
are reproduced verbatim from the Idaho Rules of Civil Procedure, adopted by the
Supreme Court of Idaho. Last verified July 14, 2026. ·
Official source
Also known as: misjoinder of partiesadd or drop a partysever claims in a lawsuitwrong party named in complaintfix a party mistake