ancillary jurisdiction

Ancillary jurisdiction allows a federal court to hear a claim that would normally be outside of its subject-matter jurisdiction if it is substantially related to a second claim that is within the court's jurisdiction. A claim comes within a federal court’s ancillary jurisdiction when it bears "a logical relationship to the aggregate core of operative facts" of the main claim, and the main claim meets the requirements of federal question jurisdiction, or diversity jurisdiction.

See: e.g., Revere Copper Brass v. Aetna Cas. Sur. Co. (1970); Hendrickson v. U.S 791 F.3d 354 (2015)

[Last reviewed in November of 2024 by the Wex Definitions Team]

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