What must federal courts have before they can hear a case related to claims arising from state law?

Federal courts require either diversity of citizenship or a federal question to have jurisdiction over cases involving state law claims. Diversity of citizenship exists when the parties are from different states, and the amount in controversy exceeds $75,000, allowing federal courts to hear the case under diversity jurisdiction. Alternatively, if a federal question is present, meaning the case involves a claim arising under the Constitution, federal laws, or treaties, federal courts are also authorized to take up the matter.

Proof of substantial damages, a unanimous jury decision, or prior adjudication in state courts do not establish the jurisdictional basis necessary for federal courts to hear a case. These elements may be relevant within the context of case proceedings or outcomes but do not impact the initial jurisdictional requirements necessary for a federal court to accept a case concerning state law claims.