Rule 20.Permissive Joinder of Parties

Rule 20(a) sets the same basic test for joining plaintiffs together and for joining defendants together. Plaintiffs may join in one action if they assert a right to relief jointly, severally, or in the alternative arising out of the same transaction, occurrence, or series of transactions or occurrences, and a question of law or fact common to all of them will come up in the case. Defendants — and property subject to an in rem proceeding — can be joined on the identical footing: a right to relief asserted against them jointly, severally, or in the alternative out of the same transaction or occurrence, plus a common question running through all their claims.

Joinder under this rule does not force an all-or-nothing outcome. Rule 20(a)(3) makes clear that no plaintiff has to want everything demanded and no defendant has to be defending against all of it; the court can enter judgment for one or more plaintiffs according to their own rights and against one or more defendants according to their own liabilities, even within a single joined action.

Because joining several parties together can create unfairness for someone caught up in a case that has nothing to do with them, Rule 20(b) gives the court a safety valve: it can issue orders — including ordering separate trials — to protect a party from embarrassment, delay, expense, or other prejudice caused by being joined with someone against whom that party asserts no claim and who asserts no claim against it.