concurring.
West Virginia officials induced sister States to contract with her and Congress to consent to the Compact. She now attempts to read herself out of this interstate Compact by reading into her Constitution a limitation upon the powers of her Governor and Legislature to contract.
West Virginia, for internal affairs, is free to interpret her own Constitution as she will. But if the compact system is to have vitality and integrity, she may not raise an issue of ultra vires, decide it, and release herself from an interstate obligation. The legal consequences which flow from the formal participation in a compact consented to by Congress is a federal question for this Court.
West Virginia points to no provision of her Constitution which we can say was clear notice or fair warning to Congress or other States of any defect in her authority to enter into this Compact. It is a power inherent in sovereignty limited only to the extent that congressional consent is required. Rhode Island v. Massachusetts, 12 Pet. 657, 725; Poole v. Fleeger, 11 Pet. 185, 209. Whatever she now says her Constitution means, she may not apply retroactively that interpretation to place an unforeseeable construction upon what the other States to this Compact were entitled to believe was a fully authorized act.
*36Estoppel is not often to be invoked against a government. But West Virginia assumed a contractual obligation with equals by permission of another government that is sovereign in the field. After Congress and sister States had been induced to alter their positions and bind themselves to terms of a covenant, West Virginia should be estopped from repudiating her act. For this reason, I consider that whatever interpretation she may put on the generalities of her Constitution, she is bound by the Compact, and on that basis I concur in the judgment.