Article III, Section 1 of the federal Constitution vests the judicial power of the United States in “one supreme Court and in such inferior Courts as the Congress may from time to time ordain and establish.” Section 2 of Article III extends the judicial power 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.” Nowhere in the Constitution, however, is “Cases, in . . . Equity” defined. No statute enacted by Congress has defined what a “case in equity” is.
Section 11 of the Judiciary Act of 1789 merely provided that circuit courts would have “cognizance . . . of all suits of a civil nature at common law or in equity” in cases appropriately brought in those courts. Neither Congress nor the courts have ever attempted to define an “equity case” or a “suit in equity” . . . .