Federal subject-matter jurisdiction questions reward careful classification. The hard part is often deciding which jurisdictional path is available, whose citizenship matters, what claims can travel together, and whether removal changes the analysis.
Practice in Testify →Ask whether the plaintiff’s own claim arises under federal law. If not, test complete diversity and amount in controversy. Then analyze any additional claims under supplemental jurisdiction. If the case began in state court, separately ask whether removal was permitted and whether a procedural or subject-matter defect requires remand.
Common distractors rely on a federal defense to create federal-question jurisdiction, confuse residence with citizenship, overlook the citizenship rules for business entities, or assume supplemental jurisdiction can cure the absence of original jurisdiction. Removal questions also tempt students to ignore who removed, when, and on what jurisdictional basis.
Make a small party-and-claim chart. Record each party’s citizenship, each claim, and the source of original jurisdiction. Then add supplemental and removal issues only after the original-jurisdiction question is resolved.
On law school exams, subject-matter jurisdiction often appears inside a longer pleading or joinder problem. State the original jurisdiction basis first, then explain whether additional claims fit supplemental-jurisdiction rules.
For bar review, pair this topic with removal and Erie practice. The exam often rewards recognizing that the federal court can hear the case before asking what law the court should apply.