Rule 18 and Party Joinder

Rule 18 and Party Joinder

Rule 18(a) lets a party asserting a claim, counterclaim, crossclaim, or third-party claim join "as many claims as it has against an opposing party."¹ The last four words set the limit: the rule reaches only an adversary who is already in the lawsuit. It tells a claimant which claims to add against that adversary. It does not tell a claimant who may become one.

Rule 20(a) answers the second question and generally governs the initial party structure of a federal case.² Under Rule 20(a)(1), plaintiffs may join as coplaintiffs only if their claims arise out of the same transaction or occurrence (or series of them) and involve a common question of law or fact. Rule 20(a)(2) applies the same two criteria to defendants sued together.³ One court called the purpose of the rule unmistakable: to promote trial convenience by avoiding multiple lawsuits, extra expense to the parties, and loss of time to the court and the litigants.⁴ Rule 18(a) states neither criterion, because it operates only after the parties are in place.

The two rules set different thresholds because they carry different risks. Forcing joinder of parties raises many problems, but most of them do not arise when a party adds a claim against someone who is already properly before the court.⁵ The generous reach of claim joinder also fits the history of these devices. They began in equity, whose courts, unlike the common-law courts, did not aim to reduce litigation to the fewest possible issues, and procedural reform in England and the United States extended them, especially the devices that let complex cases be resolved in a single action.⁶

The two rules were not always kept apart. "The only real difficulty in joinder of parties," one authority observes, "has come in cases involving both multiple parties and multiple claims," where, before a 1966 amendment, some decisions unfortunately read Rule 20(a) as limiting Rule 18.⁷ The reading had surface appeal. Rule 20(a) speaks of a common transaction, so a court might conclude that every claim in a multiparty case must share one. That conclusion would have turned a rule that screens persons into a ceiling on claims between persons who had already passed the screen.

The first two steps do all the filtering; the last two do none.

The rent claim illustrates a general pattern. Once one claim properly ties all the defendants together through a transaction in which each was involved, the plaintiff may join any claim held against any one of them, subject to the court's power to order severance.⁸ It is essential only that at least one claim arose out of that shared transaction; the others need not.⁹ Rule 18(a) adds claims and never adds persons.

Examinees go wrong in one of two directions. Some treat the openness of Rule 18(a) as if it lowered the price of admission for a new party. Others treat the same-transaction requirement of Rule 20(a) as a ceiling on the claims that may be added once everyone is in. Both errors forget that one rule filters persons and the other operates freely among those who have passed.