Rule 20.Permissive Joinder of Parties

Enacted effective October 1, 2011 · Last verified June 26, 2026

In one sentenceRule 20 lets multiple plaintiffs or defendants be joined in one action when their claims arise out of the same transaction or series of transactions and share a common question of law or fact.

Full Text of Rule 20

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(a ) Persons Who May Join or Be Joined. (1) Plaintiffs. Persons may join in one action as plaintiffs if: (A) they assert any right to relief jointly, severally, or in the alternative with respect to or arising out of the same transaction, occurrence, or series of transactions or occurrences; and (B) any question of law or fact common to all plaintiffs will arise in the action. (2) Defendants. Persons may be joined in one action as defendants if: (A) any right to relief is asserted against them jointly, severally, or in the alternative with respect to or arising out of the same transaction, occurrence, or series of transactions or occurrences; and (B) any question of law or fact common to all defendants will arise in the action. (3) Extent of Relief. Neither a plaintiff nor a defendant need be interested in obtaining or defending against all the relief demanded. The court may grant judgment to one or more plaintiffs according to their rights, and against one or more defendants according to their liabilities. (b ) Protective Measures. The court may issue orders -- including an order for separate trials -- to protect a party against embarrassment, delay, expense, or other prejudice that arises from including a person against whom the party asserts no claim and who asserts no claim against the party.

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Plain-English Summary

Rule 20 is about efficiency: when several people's claims are bound up together, they can be litigated in a single case. Plaintiffs may join together, and defendants may be joined, when two conditions are met — the claims arise out of the same transaction, occurrence, or series of them, and there is a common question of law or fact.

Joined parties need not each be interested in all of the relief; the court can grant judgment to and against parties according to their individual rights and liabilities. To prevent unfairness from lumping parties together, the court may order separate trials or other protective measures.

Frequently Asked Questions

When can multiple plaintiffs sue together?

When their claims arise out of the same transaction, occurrence, or series of transactions or occurrences, and at least one question of law or fact common to all of them will arise in the action.

Can the court separate improperly combined parties?

Yes. The court may order separate trials or issue other protective orders to prevent embarrassment, delay, expense, or prejudice.

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: permissive joinderjoinder of partiesmultiple plaintiffsmultiple defendants