Rule 17.Parties plaintiff and defendant; capacity

Rule 17(a) starts with the baseline rule: an action must be prosecuted in the name of the real party in interest. But the rule then lists who counts as that party without joining the person benefiting from the suit. An executor, administrator, guardian, bailee, or trustee of an express trust can sue in their own name, as can a party with whom or in whose name a contract was made for another's benefit, or a party a statute authorizes to sue. When a federal statute directs it, an action for the use or benefit of another proceeds in the name of the United States.

Rule 17(a) also builds in a safety valve. A court can't dismiss a case just because it wasn't brought in the real party's name until a reasonable time has passed after objection, giving that party a chance to ratify the filing, or to join or be substituted in. Once that ratification, joinder, or substitution happens, it carries the same effect as if the suit had been filed in the real party's name from the start.

Rule 17(c) turns to infants and incompetent persons. If one already has a representative — a general guardian, trustee, committee, conservator, or similar fiduciary — that representative can sue or defend on the infant's or incompetent person's behalf. Without a representative, the infant or incompetent person can sue through a next friend or a guardian ad litem. And the court itself carries a duty here: it must appoint a guardian ad litem for an infant or incompetent person who isn't otherwise represented, or enter whatever other order it thinks proper to protect that person.