Rule 20.Permissive Joinder of Parties

Last amended December 1, 2007 · Last verified June 30, 2026

In one sentenceRule 20 allows plaintiffs or defendants to be joined in one action when the claims arise out of the same transaction or occurrence and share a common question of law or fact, and it lets the court protect parties from prejudice in joined cases.

Full Text of Rule 20

Text sizeJump to: (a) (b)

(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—as well as a vessel, cargo, or other property subject to admiralty process in rem—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.

End

Amendment History

(Amended February 28, 1966, effective July 1, 1966; March 2, 1987, effective August 1, 1987; April 30, 2007, effective December 1, 2007.)

Plain-English Summary

Rule 20 sets when separate people can sue or be sued together. Plaintiffs may join in one action if they assert claims arising out of the same transaction, occurrence, or series of transactions or occurrences and their claims share a common question of law or fact. The same two-part test governs joining multiple defendants.

Joinder under Rule 20 is optional, not required — it is the counterpart to the mandatory joinder of Rule 19. To prevent unfairness or confusion from lumping parties together, the court may order separate trials or enter other orders so that a party is not embarrassed, delayed, or put to expense by claims that do not involve it.

Frequently Asked Questions

When can multiple plaintiffs or defendants join one lawsuit?

When their claims arise out of the same transaction, occurrence, or series of them, and there is a common question of law or fact (Rule 20(a)).

Is joinder under Rule 20 required, or can a party choose not to join?

It's optional. Rule 20 permits joinder when its test is met; it does not require it, unlike the mandatory joinder Rule 19 imposes for parties needed for complete relief.

Source & verification. The rule text and amendment history are reproduced verbatim from the official Federal Rules of Civil Procedure (Fed. R. Civ. P. 20), a public-domain work of the U.S. Government. Prescribed by the United States Supreme Court under the Rules Enabling Act. The plain-English summary is original and written by us. Last verified June 30, 2026. · Official source

Also known as: FRCP 20Fed. R. Civ. P. 20permissive joinder of partiesjoining plaintiffs or defendantssame transaction or occurrence