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 Non-Joinder of Parties
Enacted effective October 1, 2011 · Last verified June 26, 2026
In one sentenceRule 21 provides that misjoining parties is never a ground for dismissing a case; instead, the court may add or drop a party, or sever a claim, at any time on just terms.
Full Text of Rule 21
Plain-English Summary
Rule 21 is a short safety valve. Getting the parties wrong — joining one who doesn't belong, or leaving one out — is not a reason to throw out the case. Instead, on a motion or on its own, the court may at any time, on just terms, add or drop a party, and it may sever any claim against a party to be tried separately.
Frequently Asked Questions
Can a case be dismissed because the wrong parties were joined?
No. Misjoinder of parties is not a ground for dismissal. The court instead adds or drops parties, or severs claims, on just terms.
Can the court sever a claim?
Yes. On motion or on its own, at any time and on just terms, the court may sever a claim against a party so it proceeds separately.
Source & verification. Reproduced verbatim from the Montana Code Annotated as
published by the State Law Library of Montana and the Montana Legislature. This rule has not been amended since its adoption.
Adopted by the Supreme Court of Montana (AF 07-0157). Last verified June 26, 2026. ·
Official text
Also known as: misjoindernonjoinderseverseverance