The failure to prohibit suits against officers of a state must, therefore, have been intentional. Indeed, it is highly improbable that any one at the time conceived that the language adopted was broad enough to prohibit suits against officers of a state. On the contrary, it is proper to assume that the framers of the eleventh amendment did not intend to permit an officer of a state, while acting under the color or excuse of an unconstitutional state statute, to invade or deny any right guaranteed by the Constitution of the United States, or that such a state officer should be immune from suit in a court of the United States merely because he was acting in a representative capacity as an agent of the state. The courts of the United States were specially charged with the preservation of the Constitution, so far, indeed, as it can be preserved by judicial authority. The "Federalist" shows how clearly it was contemplated that the federal courts were to have power to overrule state statutes in manifest contravention of the Constitution. If state officers were withdrawn from the jurisdiction of the national courts, their oath to support the Constitution of the United States might become a mere empty ceremony of no enforceable obligation or sanction. If officers of a state could not be sued in equity in a federal court in an action to enjoin the enforcement of unconstitutional state statutes, many of the provisions of the Constitution, of equal authority with the eleventh amendment, might not be effectually enforceable except by the grace of the states. The prohibitions against the states, which existed when the eleventh amendment was adopted, such as that no state shall emit bills of credit, or make anything but gold and silver coin a tender in payment of debts, or pass any bill of attainder, or any ex post facto law, or any law impairing the obligation of contracts, or lay imposts or duties on imports or exports, might to a great extent be nullified and rendered practically ineffective, if officers of a state could not be sued in a federal court. Indeed, the thirteenth, fourteenth and fifteenth amendments would be deprived of a great part of their intended effect if state officers enforcing unconstitutional state laws and clothed with the power of the state could not be sued and enjoined in a federal court.