Conn. Practice Book § 9-21 (2026)

Sec. 9-21. —Counterclaim; Third Parties When a counterclaim raises questions affecting the interests of third parties, the defendant may, and if required by the judicial authority shall, cause such parties to be summoned in as parties to such suit. (See General Statutes § 52-110 and anno- tations.) (P.B. 1978-1997, Sec. 102.)