by John Marshall Harlan

“ Was he, at the commencement of this suit, a citizen of Tennessee? It is true, as contended by the defendant, that a citizen of the United States can instantly transfer his citizenship from one state to another, (Cooper v. Galbraith, 3 Wash. C. C. 546, 554,) and that his right to sue in the courts of the United States is none the less because his change of domicile was induced by the purpose, whether avowed or not, of invoking, for the protection of his rights, the jurisdiction of a federal court. ”

“ It is unnecessary to decide whether the circuit court erred in overruling the plea of former adjudication, or in rendering the decree appealed from; for we are of opinion that the motion to dismiss the suit, as one not really involving a controversy within its jurisdiction, should have been sustained. ”

“ While under the judiciary act of 1789 an issue as to the fact of citizenship could only be made by a plea in abatement, when the pleadings properly averred the citizenship of the parties, the act of 1875 imposes upon the circuit court the duty of dismissing a suit, if it appears at any time after it is brought, and before it is finally disposed of, that it does not really and substantially involve a controversy of which it may properly take cognizance. ”