§ 389.Generally

Not every joinder question is optional. Section 389 identifies the people a case cannot go forward without at all — often called necessary or indispensable parties — and tells the court what to do when one of them cannot be brought in.

Subdivision (a) defines who must be joined, so long as joining them is possible without depriving the court of subject matter jurisdiction: someone whose absence would prevent complete relief among the existing parties, or someone who claims an interest in the subject of the action and whose absence might, as a practical matter, impair that person’s ability to protect the interest, or leave the existing parties exposed to a real risk of double, multiple, or inconsistent obligations because of the absent person’s claim. If such a person has not been joined, the court orders that they be made a party.

Subdivision (b) addresses the harder case — the person described in subdivision (a) cannot be joined at all, often because the court lacks personal jurisdiction over them. The court must then decide, in equity and good conscience, whether to proceed among the parties already before it or dismiss the action without prejudice, treating the absent person as indispensable. Four factors guide that call: how prejudicial a judgment reached without the absent person would be to that person or to the existing parties; whether protective provisions in the judgment, shaped relief, or other measures could lessen that prejudice; whether a judgment reached without the absent person would still be adequate; and whether the plaintiff or cross-complainant would have an adequate remedy if the court dismissed the case for nonjoinder instead.

Subdivisions (c) and (d) round out the procedure: a complaint or cross-complaint must name any known person described in subdivision (a) who has not been joined and explain why, and nothing in § 389 disturbs the separate law governing class actions.