Common-Nucleus-of-Operative Fact Test Law and Legal Definition

Common-nucleus-of-operative fact test is a legal doctrine which says that a federal court will have jurisdiction over state law claims. A federal court can exercise its jurisdiction over those state law claims that arise from the same facts as the federal claims. The common nucleus of operative fact test was first adopted in United Mine Workers v. Gibbs, 383 U.S. 715 (U.S. 1966). It is also codified at 28 USCS § 1367.

The Common-nucleus-of-operative fact test is not merely restricted to inquire whether a federal court has power to hear the nonfederal claims along with the federal ones. The test also examines the posture in which the nonfederal claim is asserted. [Ahearn v. Charter Twp., 1998 U.S. App. LEXIS 13445 (6th Cir. Mich. June 18, 1998)].