The Supreme Court’s original jurisdiction is limited to a narrow but important range of cases. The grant of appellate jurisdiction under Article III is far broader, although Congress has some discretion to modify it. However, the Court has been assiduous in protecting the Constitution’s core grant of original jurisdiction from congressional expansion. The Court declared in Marbury v. Madison (1803) that Congress cannot add to the Supreme Court’s original jurisdiction. Under Section 13 of the Judiciary Act of 1789, Congress had granted the Court mandamus power (the power to order lower courts or executive officials to perform duties required by law). In Marbury, Chief Justice John Marshall held that the mandamus power as applied to executive officials was actually a grant of original jurisdiction, and that Congress could not constitutionally expand the original jurisdiction of the Supreme Court. Writing for the Court, the chief justice declared Section 13 unconstitutional and denied the relief sought. Marshall’s carefully crafted opinion rein-forced the significance of original jurisdiction by (1) limiting its scope to the categories of cases contained in the text and, as a consequence, (2) shifting its focus from executive matters to suits between states. Similarly, in Hodgson v. Bower-bank (1809), Marshall, invalidated Section 11 of the Judiciary Act of 1789 because it provided for federal jurisdiction “in all suits in which an alien is a party,” and that section also unconstitutionally extended Article III jurisdiction.

The Original Jurisdiction Clause has both theoretical and practical importance. Although Marshall’s opinion is an example of textual interpretation, it also made practical sense that Article III should limit the power of Congress to add to the Court’s original jurisdiction. If Congress could have expanded the Court’s original docket, citizens would have been forced to litigate in the national capital, which was often inconvenient and distant. But even as narrowly written and construed, in state-versus-state cases original jurisdiction still played an indispensable role in eliminating the bias and parochialism of state courts and lower federal courts (where judges were likely to be drawn from the same pool of local lawyers). The need for original federal power in state-versus-state cases had been a concern of the Constitution’s drafters: “Whatever practices may have a tendency to disturb the harmony between the States are proper objects of federal superintendence and control.” The Federalist No. 80.

While Congress cannot add to the Supreme Court’s original jurisdiction, the Court has accepted a reduction of the power through Congress’s creation of concurrent jurisdiction with lower federal courts over some kinds of original matters (suits against ambassadors and consuls and suits between the United States and a state, for example). Parochial biases are less prevalent in these cases and, in any event, when filed in the lower federal courts, these cases can later be transferred to the Court’s appellate docket. The current jurisdictional statute, 28 U.S.C. § 1251, sends controversies between two or more states exclusively to the Supreme Court and provides for concurrent jurisdiction over all other categories of original cases.

From the beginning, the most important suits between states were disputes over boundaries. These suits presented precisely those situations where the forces of provincialism and self-interest were most likely to compromise a state or lower federal court. Between 1790 and 1900, boundary disputes were the only suits between states the Court heard on its original docket. By the twentieth century, the category of original disputes expanded to include other important matters, such as water-rights cases and Commerce Clause claims (related to the use of state economic, regulatory, or tax powers). These kinds of cases continue to this day. See, e.g., Maryland v. Louisiana (1981), which deals with Louisiana’s severance tax on natural gas. On occasion, when purely legal and urgent constitutional challenges are raised, the Court has also permitted suits to be filed on an original basis by states against the United States. See South Carolina v. Katzenbach (1966) (the Voting Rights Act of 1965).

Original cases are not heard before the Supreme Court as of right, even though its jurisdiction is exclusive. Original cases are commenced by a petition for leave to file a complaint. Such petitions are frequently denied, sometimes because the Court believes that a matter between states is too trivial (e.g., whether state universities breached a contract to play football) or, conversely, when the Court considers that the subject matter is too broad or unmanageable (e.g., issues of interstate water or air pollution) or simply because the Court is not ready to hear the matter.

Once the Court grants the states’ petitions to file a complaint, it usually appoints a special master to make factual and legal recommendations. The special master, in turn, holds hearings and takes testimony, guided in a general way by the Federal Rules of Civil Procedure and the Federal Rules of Evidence. See Rule 17 of the Rules of the Supreme Court of the United States (2010). Unlike appeals of district court decisions under the Federal Rules of Civil Procedure, the master is given no formal deference on findings of fact by the Supreme Court, although such findings are often accepted by the Court. The parties also present briefs, arguments, and pro-posed recommendations, after which the special master issues a final report. The parties can take exceptions to that report to the Supreme Court, where it is briefed and argued and proceeds much like a traditional appellate or certiorari case. One issue of continuing interest is whether non-state entities, ranging from water districts to cities to private parties, are allowed to intervene in original cases. The Court monitors such requests closely. See South Carolina v. North Carolina (2010).

There have been fewer than two hundred state-versus-state original cases in the history of the republic, less than one per year of the Constitution’s life. There have been only two original cases under the “affecting Ambassadors” section of the clause. Despite these relatively modest numbers, original jurisdiction continues to serve an indispensable purpose in resolving matters of high moment between states. No forum other than the Supreme Court can act with the authority and dignity necessary to resolve what are in effect diplomatic encounters between contending sovereigns under our constitutional system.