Original jurisdiction means that a case begins in the court. District courts exercise original jurisdiction over many federal-question cases, in which a claim arises under federal law, and over qualifying diversity cases. Under the current diversity statute, an ordinary civil action must satisfy the citizenship rules and place more than $75,000 in controversy, excluding interest and costs. Federal criminal prosecutions also begin in district court. The Supreme Court has constitutionally specified original jurisdiction over a small category of cases, including disputes between states, but it is not the ordinary national trial court, and Congress may neither enlarge nor contract that constitutional category by ordinary statute.

Federal-question and diversity jurisdiction serve different purposes. A federal question ordinarily appears in the plaintiff's properly pleaded claim and arises under the Constitution, a federal statute, or a treaty. Diversity jurisdiction provides a federal forum for qualifying disputes, subject to requirements such as complete diversity and the amount in controversy. The presence of a federal defense ordinarily does not turn a state-law complaint into a federal-question case. Identify what creates the plaintiff's claim, not simply a federal issue that might appear later.

Original jurisdiction does not always mean exclusive jurisdiction. State courts can hear many federal claims unless Congress has validly made federal jurisdiction exclusive, and some cases can be removed from state to federal court when statutory requirements are satisfied. The court in which a case begins, the system authorized to hear it, and the system with exclusive authority are therefore separate facts.

Ask two separate questions. First, does the claim fall within the constitutional judicial power? Second, has Congress authorized this court to exercise jurisdiction? Article III sets an outer boundary; federal statutes do much of the operational routing. A claim can involve nationally important facts and still belong in state court if no basis for federal jurisdiction exists.

Personal jurisdiction and venue should not be collapsed into subject-matter jurisdiction. Subject-matter jurisdiction concerns the category of dispute. Personal jurisdiction concerns authority over the defendant, and venue identifies the proper geographic forum. A question may satisfy one requirement and fail another.

Worked application. Two citizens of the same state dispute a local contract, and neither raises federal law. The amount at stake is enormous. Importance and dollar value alone do not create federal subject-matter jurisdiction. By contrast, a modest claim directly arising under a federal civil-rights statute can present a federal question even if the parties live in the same state. The two pathways are alternatives: a case does not need diversity when a valid federal question already supplies jurisdiction.

The exam shortcut is not "federal topic equals federal court." Ask what law creates the claim and which statute grants the court power. That discipline prevents political importance, party preference, or a large amount of money from masquerading as jurisdiction.

Video lesson: Structure of the Court System: Crash Course Government and Politics #19