Felix Frankfurter

“ The diversity jurisdiction of the federal courts was probably the most tenuously founded and most unwillingly granted of all the heads of federal jurisdiction which Congress was empowered by Article III to confer. It is a matter of common knowledge that the jurisdiction of the federal courts based merely on diversity of citizenship has been more continuously under fire than any other. ”

“ In the exercise of its constitutional power to regulate commerce, to establish uniform rules of naturalization, to raise and support armies, or to execute any of the other powers of Congress that are no less vital than its power to legislate for the District of Columbia, the Congress may be greatly in need of informed and disinterested legal advice. ”

“ Insofar as the courts established under Article III can entertain a case not involving the Constitution, the laws of the United States or treaties, nor concerning admiralty, they do so because of the status of the parties, enumerated with particularity in Article III.
We are here concerned with the power of the fedeal courts to adjudicate merely because of the citizenship of the parties. Power to adjudicate between citizens of different states, merely because they are citizens of different states, has no relation to any substantive rights created by Congress. ”