At the Constitutional Convention, William Paterson put forward the New Jersey Plan designed to counter the more nationalist plan set out by Virginia. Despite its focus on the rights of the states, Paterson’s plan nonetheless acknowledged the necessity of national competency and supremacy in a number of areas. It proposed to authorize, for example, the federal judiciary to hear appeals from state courts in “all cases touching the rights of Ambassadors.” The provision excited no discussion, and the Committee of Detail penned the final version, including placing the subject within the original jurisdiction of the Supreme Court. (See Article III, Section 2, Clause 2.)

All, including the Anti-Federalist Brutus, seemed to agree with the sentiments of Alexander Hamilton that placing the jurisdiction of cases dealing with foreign ministers had “an evident connection with the preservation of the national peace.” The Federalist No. 80. Justice Joseph Story in his Commentaries on the Constitution of the United States (1833) thought that every question involving the “rights, powers, duties, and privileges” of public ministers was “so intimately connected with the public peace, and policy, and diplomacy of the nation, and touches the dignity and interest of the sovereigns of the ministers concerned so deeply, that it would be unsafe, that they should be submitted to any other, than the highest judicature of the nation.”

In Osborn v. Bank of the United States (1824), the Supreme Court declared that the foreign diplomat need not be a party to the case to trigger federal jurisdiction, although original jurisdiction is not mandated when the diplomat is merely a victim of a crime. United States v. Ortega (1826). Federal jurisdiction under this clause applies to foreign, not United States, diplomats, Ex parte Gruber (1925). It does not apply to divorce suits involving foreign diplomats, Ohio ex rel. Popovici v. Agler (1930), or to suits involving former foreign diplomatic agents or those whose tours of duty in the United States have ended, Farnsworth v. Sanford (1941). Furthermore, although the Ambassadors Clause speaks of “Ambassadors, other public Ministers and Consuls,” as early as 1890 the Supreme Court held that consuls representing foreign countries but who are United States citizens invested with only commercial duties are not subject to this provision. In re Baiz (1890). Under modern practice, consuls in general are not normally regarded as diplomatic agents.

The fact that the Constitution lodges these cases in the federal judiciary does not preclude the foreign diplomatic agent from pleading diplomatic immunity. Under traditional international law principles, codified in the Vienna Convention on Diplomatic Relations (1961), accredited foreign ambassadors and other ministers may plead immunity from suits in the courts of the host country. The United States became a party to the Convention in 1972, and in 1978 Congress passed the Diplomatic Relations Act implementing the Vienna Convention. In addition, Congress decided that there was no justification for continuing to vest original jurisdiction solely in the Supreme Court and gave district courts concurrent original jurisdiction over civil actions brought against members of diplomatic missions and their families. Actions initiated by foreign diplomats or their families, however, remain solely under the original jurisdiction of the Supreme Court.