The Supreme Court of the United States has always declared that subject matter jurisdiction - the authority granted a federal court to reach and decide the merits of a dispute - is an absolutely necessary precondition to the exercise of judicial power by Article III courts. But in significant cases, forming a tradition with its own deep roots, the Court appears to act on a vision of jurisdiction that is far more fluid, contingent, and subject to the Court’s own notions of which merits questions should be resolved finally by federal courts. This seminar will consider cases where the Court stands behind its rhetoric identifying jurisdiction as a strict limit on Article III power and also cases where the Court has softened that stance to pursue other ends. Examples will include special problems of justiciability, the Supreme Court’s review of state-court state-law judgments, and the strange path of the Erie doctrine.