The judicial authority may determine the controversy as between the parties before it, if it can do so without prejudice to the rights of others; but, if a complete determination cannot be had without the presence of other parties, the judicial authority may direct that they be brought in. If a person not a party has an interest or title which the judgment will affect, the judicial authority, on its motion, shall direct that person to be made a party. (See General Statutes § 52-107 and annotations.)
Section 9-18.Addition or Substitution of Parties; Additional Parties Summoned in by Court
Current through August 12, 2025 (2026 Practice Book edition) · Last verified July 9, 2026
In one sentenceThis rule lets a court settle a case using only the parties before it when that is possible, but requires the court to bring in any outside person whose interest or title the judgment would affect.
Full Text of Section 9-18
Amendment History
(P.B. 1978-1997, Sec. 99.)
Plain-English Summary
Section 9-18 gives the judicial authority two related powers over who belongs in a lawsuit. First, if the court can resolve the dispute between the existing parties without hurting anyone else’s rights, it may go ahead and decide the case as is. But if a full, fair resolution is impossible without someone who isn’t currently in the case, the court may order that person brought in.
Second, the rule imposes an affirmative duty on the court, not just a discretionary option: if a person who isn’t a party holds an interest or title that the judgment will affect, the court must, on its own motion, direct that the person be made a party. The court doesn’t need either side to ask — it can act to protect a nonparty’s rights before entering judgment.
Frequently Asked Questions
Can a Connecticut court decide a case without every interested person joined?
Yes, if the court can reach a complete and fair resolution among the parties already before it without harming anyone else’s rights, it may proceed without adding more parties.
When must a court add a new party on its own, without a motion?
When a nonparty holds an interest or title that the judgment will affect, Section 9-18 requires the court to direct that person be made a party on its own motion.
What happens if a necessary party is left out of a Connecticut lawsuit?
The court may direct that the missing person be brought in so the case can be fully determined; Section 9-19 also makes clear that the case isn’t automatically defeated by such a gap.
Source & verification. The section text is reproduced verbatim from the
official Connecticut Practice Book (Conn. Practice Book § 9-18). Prescribed by the Judges of the Superior Court of Connecticut (Conn. Gen. Stat. Section 51-14). The plain-English summary is original and written by us. Last verified July 9, 2026. ·
Official source
Also known as: adding necessary parties Connecticutcourt orders new party joinedparty whose interest judgment affectscomplete determination of controversy CTcite in party on court's own motion