the jurisdiction under which a federal court is permitted to decide an entire controversy (including matters which it would not have authority to consider were they raised independently) if the controversy contains other issues that the law specifically authorizes federal courts to decide. Thus, when the court has jurisdiction of the principal action, it may also hear any ancillary proceeding, regardless of any other factor that would normally determine jurisdiction.
Compare pendent jurisdiction.
Source: Barron's Dictionary of Legal Terms, Steven H. Gifis, 5th Edition; © 2016
"When a party brings a claim of retaliation in conjunction with a Title VII claim, the party asks the court to exercise ancillary jurisdiction over the retaliation claim. See Gupta v. East Tex. State Univ., 654 F.2d 411, 413-14 (5th Cir. 1981) (district court has ancillary jurisdiction to hear retaliation claim growing out of earlier charge of Title VII violation)."
- Jones v. Runyon , 91 F.3d 1398 (10th Cir. 1996)