Rule 17.Parties Plaintiff and Defendant: Capacity
Effective July 1, 1974 · Last amended January 2, 2012 · Last verified June 26, 2026
Full Text of Rule 17
Rule History
Effective July 1, 1974. Amended June 24, 2009, effective July 1, 2009; amended December 14, 2011, effective January 2, 2012.
Reporter’s Notes
(2012)
The rule is updated to reflect terminology changes introduced by the Massachusetts Uniform Probate Code, G.L. c. 190B.
(2009)
The 2009 amendments reflect changes resulting from the adoption of the Massachusetts Uniform Probate Code.
(1973)
Rule 17 is a modified version of Federal Rule 17; the requirement that actions be prosecuted in the name of the real party in interest is new to Massachusetts law. At common law in Massachusetts, the subrogee had no right to sue the tortfeasor in his own name. His rights were considered equitable in nature, entitling him to bring the action only in the insured's name. See Gray v. United States, 77 F.Supp. 869 (D.Mass.1948), reversed on other grounds, 172 F.2d 737 (1st Cir.1949). By statute (G.L. c. 231 § 5), the assignee of a non-negotiable legal chose in action which has been assigned in writing may maintain an action thereon in his own name. With several exceptions, Rule 17(a) makes compulsory a suit in the name of the real party in interest. One of the exceptions is not contained in Federal Rule 17: “An insurer who has paid all or part of a loss may sue in the name of the assured to whose right it is subrogated.”
The second sentence in Rule 17(a) does not really qualify the first sentence. Individuals such as executors, bailees, trustees, etc. have a “real interest” in the litigation.
The last sentence of Rule 17(a) permits a reasonable time for ratification by, or joinder or substitution of, the real party in interest. It tracks a 1966 amendment to Federal Rule 17(a). This provision is consistent with Massachusetts practice, which allows amendments as to parties (G.L. c. 231 § 51).
Rule 17(b), which copies Federal Rule 17(c) without change, accords with prior Massachusetts law. See G.L. c. 201. Federal Rule 17(b) is omitted from Rule 17 as inapplicable to state practice.
Plain-English Summary
Rule 17 makes the right person bring the case. As a rule, an action must be prosecuted in the name of the real party in interest—the one who owns the claim. The rule lists who may sue in their own name without joining the beneficiary: a personal representative, guardian, conservator, trustee of an express trust, and others. Massachusetts adds an exception not in the federal rule: an insurer that has paid a loss may sue in the name of the assured to whose rights it is subrogated. Workers' compensation actions under G.L. c. 152, § 15 are carved out.
A case is not dismissed for naming the wrong plaintiff right away. The court allows a reasonable time, after objection, for the real party in interest to ratify, join, or be substituted, and that step relates back as if the action had started correctly.
For those who cannot litigate on their own—an infant, an incompetent person, or an incapacitated person under the Uniform Probate Code—a representative such as a guardian or conservator may sue or defend. If there is none, the person may sue by next friend, and the court appoints a guardian ad litem to protect an unrepresented party.
Frequently Asked Questions
What does “real party in interest” mean?
The person who owns the claim and is entitled to enforce it. Rule 17(a) requires the action to be prosecuted in that person's name, with listed exceptions for representatives and others.
Can an insurer sue in the name of the insured?
Yes. Massachusetts Rule 17(a) lets an insurer that has paid all or part of a loss sue in the name of the assured to whose rights it is subrogated—an exception not found in the federal rule.
How does a minor or incapacitated person sue?
Through a representative such as a guardian or conservator. If there is none, the person may sue by a next friend, and the court will appoint a guardian ad litem to protect an otherwise unrepresented infant or incapacitated person.