Del. Ch. Ct. R. 19 (2026)

Rule 19. Required Joinder of Parties (a) Persons Required to Be Joined if Feasible. (1) Required Party. A person who is subject to service of process must be joined as a party if: (A) in that person’s absence, the Court cannot accord complete relief among existing parties; or (B) that person claims an interest relating to the subject of the action and is so situated that disposing of the action in the person’s absence may: (i) as a practical matter impair or impede the person’s ability to protect the interest; or (ii) leave an existing party subject to a substantial risk of incurring double, multiple, or otherwise inconsistent obligations because of the interest. (2) Joinder by Court Order. If a person has not been joined as required, the Court must order that the person be made a party. A person who refuses to join as a plaintiff may be made either a defendant or, in a proper case, an involuntary plaintiff. (3) Venue. If a joined party objects to venue and the joinder would make venue improper, the Court must dismiss that party. (b) When Joinder Is Not Feasible. If a person who is required to be joined if feasible cannot be joined, the Court must determine whether, in equity and good conscience, the action should proceed among the existing parties or should be dismissed. The factors for the Court to consider include: (1) the extent to which a judgment rendered in the person’s absence might prejudice that person or the existing parties; (2) the extent to which any prejudice could be lessened or avoided by: (A) protective provisions in the judgment; (B) shaping the relief; or (C) other measures;

(3) whether a judgment rendered in the person’s absence would be adequate; and (4) whether the plaintiff would have an adequate remedy if the action were dismissed for nonjoinder. (c) Pleading the Reasons for Nonjoinder. When asserting a claim for relief, a party must state: (1) the name, if known, of any person who is required to be joined if feasible but is not joined; and (2) the reasons for not joining that person. (d) Exception for Class Actions. This rule is subject to Rule 23. History. Amended, effective Sept. 25, 2023.

Rule 20. Permissive Joinder of Parties (a) Persons Who May Join or Be Joined. (1) Plaintiffs. Persons may join in one action as plaintiffs if: (A) they assert any right to relief jointly, severally, or in the alternative with respect to or arising out of the same transaction, occurrence, or series of transactions or occurrences; and (B) any question of law or fact common to all plaintiffs will arise in the action. (2) Defendants. Persons may be joined in one action as defendants if: (A) any right to relief is asserted against them jointly, severally, or in the alternative with respect to or arising out of the same transaction, occurrence, or series of transactions or occurrences; and (B) any question of law or fact common to all defendants will arise in the action. (3) Extent of Relief. Neither a plaintiff nor a defendant need be interested in obtaining or defending against all the relief demanded. The Court may grant judgment to one or more plaintiffs according to their rights, and against one or more defendants according to their liabilities.

(b) Protective Measures. The Court may issue orders—including an order for separate trials—to protect a party against embarrassment, delay, expense, or other prejudice that arises from including a person against whom the party asserts no claim and who asserts no claim against the party. History. Amended, effective Sept. 25, 2023.