Article III, Section 2, Clause 1:
The Judicial Power shall extend to all Cases, in Law and Equity, arising under this Constitution, the Laws of the United States, and Treaties made, or which shall be made, under their Authority;—to all Cases affecting Ambassadors, other public Ministers and Consuls;—to all Cases of admiralty and maritime Jurisdiction; to Controversies to which the United States shall be a Party;—to Controversies between two or more States; between a State and Citizens of another State; between Citizens of different States,—between Citizens of the same State claiming Lands under Grants of different States, and between a State, or the Citizens thereof, and foreign States, Citizens or Subjects.
A conceptually difficult doctrine, which approaches the verge of a serious constitutional gap, is the concept of protective jurisdiction. Under this doctrine, it is argued that in instances in which Congress has legislative jurisdiction, it can confer federal jurisdiction, with the jurisdictional statute itself being the
law of the United States within the meaning of Article III, even though Congress has enacted no substantive rule of decision and state law is to be applied. Put forward in controversial cases,1 the doctrine has neither been rejected nor accepted by the Supreme Court. In Verlinden B. V. v. Central Bank of Nigeria,2 the Court reviewed a congressional grant of jurisdiction to federal courts to hear suits by an alien against a foreign state, jurisdiction not within the
arising under provision of article III. Federal substantive law was not applicable, that resting either on state or international law. Refusing to consider protective jurisdiction, the Court found that the statute regulated foreign commerce by promulgating rules governing sovereign immunity from suit and was a law requiring interpretation as a federal-question matter. That the doctrine does raise constitutional doubts is perhaps grounds enough to avoid reaching it.3