It does not as distinctly appear from the bill itself as from this statement that the first action at law referred to was brought and is pending in the circuit court of the United States for the Southern district of New York. It may, however, perhaps be fairly inferred from the allegations of the bill that such is the fact; and, as it has been so assumed in the argument of the cause, no question is made upon the sufficiency of the bill in that respect. The only ground here urged in support of the decree and of the demurrer to the bill is that the complainants, upon the case made in the bill, have a complete and adequate defense at law, and that, consequently, they do not bring themselves within the jurisdiction of a court of equity.
If the decedent, Robert Berney, at the time of his death, was domiciled in France, and not in Alabama, the letters testamentary issued to his brother James Berney, as executor in Alabama, were void, and the authority given by James Berney to St. James by the power of attorney was also invalid, and the payment made by the appellants to St. James of the proceeds of the sales of the bonds which belonged to the estate does not bind the rightful executor or protect the complainants. The ground of the bill therefore is that, upon these facts, an action at law may be successfully maintained by the appellee, as executrix of Robert Berney, against the complainants for the value of the bonds. The question is whether the other facts set up in the bill furnish a complete and adequate defense to such an action at law, or whether they establish a right in equity to relief. The rule as laid down by this court in Boyce's Exr v. Grundy, 3 Pet. 210, is that 'it is enough that there is a remedy at law. It must be plain and adequate; or, in other words, as practical and efficient to the ends of justice and its prompt administration as the remedy in equity.' And, as appears by that case, the principle is as applicable in cases where a complainant resorts to a court of equity to enforce a defense to an action at law as where he seeks by a bill in equity other relief. This is illustrated by the case of Grand Chute v. Winegar, 15 Wall. 373. That was a case of a bill in equity by a municipal corporation to procure the cancellation of bonds on which an action at law had been brought, alleged to be void in the hands of the holder. The court said: 'A judgment against Winegar in the suit brought by him would be as conclusive upon the invalidity of the bonds, would as effectually prevent all future vexatious litigation, would expose the fraud, and prevent future deception as perfectly and thoroughly, as would a judgment in the equity suit. Under such circumstances, there is no authority for bringing this suit in equity.'
The ground of relief alleged in the present bill is that by her acts and conduct the appellee has estopped herself, as against the complainants, from asserting any fact which annuls the executorship of James Berney under the Alabama probate, and the authority of St. James as his attorney in fact. Estoppels of this character, as distinguished from estoppels by record or by deed, are called equitable estoppels. It is not meant thereby that they are cognizable only in courts of equity, for they are commonly enforced in actions at law, as was fully shown in Dickerson v. Colgrove, 100 U.S. 578. But it does not follow, because equitable estoppels may originate legal as distinguished from equitable rights, that it may not be necessary in particular cases to resort to a court of equity in order to make them available. All that can properly be said is that, in order to justify a resort to a court of equity, it is necessary to show some ground of equity other than the estoppel itself, whereby the party entitled to the benefit of it is prevented from making it available in a court of law. In other words, the case shown must be one where the forms of the law are used to defeat that which in equity constitutes the right. Such a case is one for equitable interposition.