(a) Permissive joinder. All persons may join in one action as plaintiffs if they assert any right to relief jointly, severally, or in the alternative in respect of or arising out of the same transaction, occurrence, or series of transactions or occurrences and if any question of law or fact common to all of these persons will arise in the action. All persons may be joined in one action as defendant if there is asserted against them jointly, severally, or in the alternative, any right to relief in respect of or arising out of the same transaction, occurrence, or series of transactions or occurrences and if any question of law or fact common to all defendants will arise in the action. A plaintiff or defendant need not be interested in obtaining or defending against all the relief demanded. Judgment may be given for one or more of the plaintiffs according to their respective rights to relief, and against one or more defendants according to their respective liabilities.
Rule 20.Permissive joinder of parties
Group 4: Parties · Last amended April 28, 2015 · Last verified July 13, 2026
In one sentenceRule 20 lets multiple plaintiffs sue together or multiple defendants be sued together whenever their claims arise from the same transaction or occurrence and share a common question of law or fact, and it sets out how a case proceeds when only some of several defendants are served.
Full Text of Rule 20
(b) Separate trials. The court may make such orders as will prevent a party from being embarrassed, delayed, or put to expense by the inclusion of a party against whom the party asserts no claim and who asserts no claim against the party, and may order separate trials or make other orders to prevent delay or prejudice.
(c) When Either Spouse or Either Domestic Partner may join. [Reserved. See RCW 4.08.040.]
(d) Service on joint defendants; procedure after service. When the action is against two or more defendants and the summons is served on one or more but not on all of them, the plaintiff may proceed as follows:
(1) If the action is against the defendants jointly indebted upon a contract, the plaintiff may proceed against the defendants served unless the court otherwise directs; and if the plaintiff recovers judgment it may be entered against all the defendants thus jointly indebted so far only as it may be enforced against the joint property of all and the separate property of the defendants served.
(2) If the action is against defendants severally liable, the plaintiff may proceed against the defendants served in the same manner as if they were the only defendants.
(3) Though all the defendants may have been served with the summons, judgment may be taken against any of them severally, when the plaintiff would be entitled to judgment against such defendants if the action had been against them alone.
(e) Procedure to bind joint debtor. [Reserved. See RCW 4.68.]
Amendment History
Prior: RPPP Rule 20. Adopted May 5, 1967, effective July 1, 1967; amended, adopted May 7, 1980, effective July 1, 1980; amended, effective April 28, 2015.
Plain-English Summary
Rule 20 is about efficiency. Rather than filing five separate lawsuits over the same car accident or the same construction defect, plaintiffs with related claims can join together in one case, and defendants who share responsibility can be sued together, as long as two things are true: the claims grow out of the same transaction, occurrence, or series of them, and there's at least one common question of law or fact running through all of them. No plaintiff or defendant has to care about every piece of relief the case demands — the rule lets the court sort out judgment for and against each party according to what that party deserves.
Joining parties this way isn't supposed to create a mess. Rule 20(b) gives the court authority to order separate trials, or otherwise manage the case, so that a party with no real stake in some part of the dispute isn't dragged through delay or expense that has nothing to do with them.
Rule 20(d) covers a practical wrinkle: what happens when a plaintiff sues two or more defendants but only manages to serve some of them. If the defendants are jointly indebted on a contract, the plaintiff can proceed against whoever was served, and any judgment reaches the joint property of all the debtors along with the separate property of the ones who were served. If the defendants are severally liable instead, the plaintiff can proceed against the served defendants exactly as if they were the only ones sued. And even when every defendant has been served, judgment can still be entered against just some of them, severally, whenever the plaintiff would have been entitled to that judgment against those defendants alone.
Two other subsections point to statutes rather than court procedure: joinder involving spouses or domestic partners is governed by RCW 4.08.040, and binding a joint debtor who wasn't served follows RCW 4.68.
Frequently Asked Questions
What's the difference between Rule 19 and Rule 20?
Rule 19 forces certain parties into a case because complete relief or fairness demands it. Rule 20 is permissive — it lets parties with related claims join voluntarily when their claims share a common transaction and a common question, but nobody is required to join.
Can a court split up claims joined under Rule 20?
Yes. Rule 20(b) lets the court order separate trials or other measures to keep one party from being delayed or burdened by claims that don't involve them.
What happens if a plaintiff sues three defendants but only serves one?
It depends on how the defendants are liable. If they're jointly indebted on a contract, the plaintiff can proceed against the one served, and any judgment reaches the joint property of all three plus the separate property of the one served. If the defendants are severally liable, the plaintiff proceeds against the served defendant as if the others weren't part of the case.
Can a plaintiff get judgment against only some served defendants?
Yes. Rule 20(d)(3) allows judgment against any served defendant severally, whenever the plaintiff would have been entitled to that judgment if that defendant had been sued alone.
Does Rule 20 require every plaintiff to want the same relief?
No. A plaintiff or defendant joined under this rule doesn't need to be interested in every form of relief the case seeks — judgment is entered according to each party's own rights and liabilities.
Source & verification. Rule text and amendment history are
reproduced verbatim from the Washington Superior Court Civil Rules, adopted by the
Supreme Court of Washington. Last verified July 13, 2026. ·
Official source
Also known as: permissive joinderjoining multiple plaintiffsjoining multiple defendantssuing joint defendantsseverally liable defendants rule