Definition - What does Ancillary Jurisdiction mean?
Ancillary jurisdiction is a term that is used to describe the jurisdiction that a federal court gets when it is forced to deal with an issue that is normally outside of its jurisdiction. This can happen when there are two issues involved in a case and when one of them is within a federal court's jurisdiction, and the other is not.
Justipedia explains Ancillary Jurisdiction
Typically, federal courts deal with federal cases, and state and local courts deal with state and local issues. However, it is not always possible to fit cases with 100% accuracy into just one of these three categories. Sometimes, a federal court must deal with a case that has multiple issues, and one of these issues may be more of a state court issue. However, the federal court still has to hear the case, and this is when ancillary jurisdiction comes into play.