Opinion of the Court
calling a sovereign state before the jurisdiction of another sovereign state.” 3 Debates on the Constitution 549 (J. Elliot ed. 1876) (Pendleton) (Elliot’s Debates). Two of the most prominent Antifederalists—Federal Farmer and Brutus—disagreed with the Federalists about the desirability of a federal forum in which States could be sued, but did so for the very reason that the States had previously been “subject to no such actions” in any court and were not “oblige[d]” “to answer to an individual in a court of law.” Federal Farmer No. 3 (Oct. 10, 1787), in 4 The Founders’ Constitution 227 (P. Kurland & R. Lerner eds. 1987). They found it “humiliating and degrading” that a State might have to answer “the suit of an individual.” Brutus No. 13 (Feb. 21, 1788), in id., at 238.
In short, at the time of the founding, it was well settled that States were immune under both the common law and the law of nations. The Constitution’s use of the term “States” reflects both of these kinds of traditional immunity. And the States retained these aspects of sovereignty, “except as altered by the plan of the Convention or certain constitutional Amendments.” Alden, 527 U. S., at 713.
2
One constitutional provision that abrogated certain aspects of this traditional immunity was Article III, which provided a neutral federal forum in which the States agreed to be amenable to suits brought by other States. Art. III, §2; see Alden, supra, at 755. “The establishment of a permanent tribunal with adequate authority to determine controversies between the States, in place of an inadequate scheme of arbitration, was essential to the peace of the Union.” Principality of Monaco v. Mississippi, 292 U. S. 313, 328 (1934). As James Madison explained during the Convention debates, “there can be no impropriety in referring such disputes” between coequal sovereigns to a superior tribunal. Elliot’s Debates 532.
