— The appellees claim freedom under a .deed of manumission, made in. the State of Maryland, in 1787. The deed attempts to provide a prospective emancipation, and is attested by only one witness. The law of Maryland, authorizing such emancipation, was a statute adopted in 1752, which was given in evidence. It is a. question in this ease, whether that act requires the attestation of two subscribing witnesses to a deed of prospective emancipation, or whether that requisition is confined to deeds, the operation of which is contemporaneous-with their delivery. The decision of this question depends upon the construction of the statute.
The law given in evidence was construed by the court of appeals of the State of Maryland, in 1807, in the case of negro James v. Gaither, 2 Harris & Johns. R. 176. The decision in that case was introduced as defensive testimony in this cause by the appellant, and is a part of the record. To show that that decision should not influence the judgment of this court, in the construction of the Maryland statute, it is argued, that the precise point now in controversy was not decided, or in the mind of the court; that it was made long after the execution of the deed, and when' the right of property in the maternal ancestor of the petitioners was exercised in another State; and that the decision is manifestly incorrect. We proceed to consider the points thus made in the order in which they are stated.
In negro James v. Gaither, supra, the sole defect in a deed of prospective emancipation was, that it was attested, by only one witness. The county court, in which the petition was filed, sustained the deed. The general court, on appeal, reversed the judgment of the county court; and the court of appeals, on appeal from the general court, affirmed its decision without delivering an opinion. The report of the case contains a brief statement of the argu*587ments in the case. The argument for the appellant seems to present to the court only the point, that the statute required merely that two persons should witness the execution of the deed; not that they should subscribe their names to it as attesting witnesses. It was contended in the discussion of this case, that the only point decided, or in the mind of the court, was that made in argument. The result of that position would be, to take from judicial decisions, where there is no opinion, the authority of an adjudication upon all propositions which were too plain, or too well recognized by the bench and bar, to be questioned; and thus the universal and undisputed sanction of a legal principle would become a barrier to proof by judicial decisions of its existence. It better accords with reason to regard a judicial tribunal as asserting, and intending to assert, every proposition which is indispensable to the conclusion expressed, and necessarily involved in it; at least when the contrary does not appear. There was one subscribing witness to the deed in the case of negro James v. Gaither. If one subscribing witness was sufficient in the judgment of the court, an affirmance was impossible. The proposition that one subscribing witness was not sufficient, is necessarily involved in the conclusion expressed; and as nothing to the contrary appears, it must be regarded as decided by the court. That the counsel placed his argument upon the ground that the statute did not require the two witnesses who “ evidenced ” the execution of the deed to be subscribing witnesses, proves rather that the necessity of two witnesses was a recognized and conceded point of law in Maryland, than that the court passed over, without observing and deciding, the proposition which was directly and necessarily involved in the judgment given.
The effect of the Maryland decision was considered by the Virginia court of appeals, in the case of Thrift v. Hannah, 2 Leigh, 800. In that case, as in this, the validity of a deed of prospective emancipation, made in Maryland, and attested by one witness, was controverted; and the Maryland decision was presented as an authoritative exposition of the meaning of the statute. The court, *588although it denied the correctness of the construction adopted in Maryland, yielded to the decision as an authoritative adjudication of the point, that two subscribing witnesses were necessary to sustain the deed. The supreme court of the United States seems to have taken the same view of the Maryland decision, in the case of Miller v. Herbert, 5 Howard, 72. We are thus, by adjudged cases, fortified in the conclusion, that the Maryland court of appeals has construed the statute as roquir-ing two subscribing witnesses to a deed of jmosjDective emancipation.
It is true, that the Maryland decision given in evidence was made about twenty years after the execution of the deed, and about three years after Matilda, the mother of one, and the grandmother of the other petitioners, had been carried to Kentucky; but these facts do not detract from the weight of the decision as evidence in the case. The validity of the deed made in 1787 is to be determined by the law of Maryland as it then existed. The statute was not necessarily all the law upon the subject. The construction placed upon the statute was also a matter of law; and it was permissible to show, as well the construction placed upon the statute, as the statute itself. — 'Walker v. Forbes, at the last term. If the decision made the law, as the statute does, it would be totally irrelevant to the case; because contracts must stand or fall, not by subsequent, but by existing law. Judicial opinions, however, do not make the law. Their office is simply to declare the law as it existed before. They are not, in themselves, law, but evidence of what the law is. There can be but one right construction of the statute. That construction was the same when the statute was adopted, as when the decision was made. The Maryland court of appeals simply declared that construction by the judgment which it gave, and is evidence of what is the proper construction. The construction, which the decision evidences, was the law from the adoption of the statute.
In the case from 2 Leigh, supra, the deed made before the Maryland decision was held void under its influence, notwithstanding the negroes, whose claim to emancipation *589was affected by it, had been removed to Virginia about nine years before the decision was made. In that case, the following emphatic language was used: “The construction given to the law of Maryland by the decision of the court of that State puts the Maryland deed of emancipation out of the case.” Chief Justice Marshall, in the case of Elmendorf v. Taylor, 10 Wheaton, said: “This court has, uniformly professed its disposition, in cases depending on the laws of a particular State, to adopt the construction which the courts of the State have given to those laws. This course is founded on the principle, supposed to be universally recognized, that the j udicial departments of every government, where such department exists, is the appropriate organ for construing the legislative acts of that government. Thus, no court in the universe, which professed to be governed by principle, would, we presume, undertake to say that the courts of Great Britain, or of France, or of any other nation, had misunderstood their own statutes; and therefore erect itself into a tribunal, which should correct such misunderstanding.” In this last case, decisions of the Kentucky court of appeals, made long after the rights of the respective parties had attached, control the judgment of the supreme court of the United States. In Shelby v. Guy, 11 Wheaton, 367, it is remarked, that a fixed and received construction of the statutes of the several States, in their respective courts, makes in fact a 'part of the statute law of the country. There are many other decisions to the same effect, some of which we cite without comment. — Johnston v. S. W. R. R. Bank, 8 Strob. Eq. 263-300; McRae v. Mattoon, 13 Pick. 53; Sidney v. White, 12 Ala. 728; Raynham v. Canton, 3 Pick. 293; Mutual Ass. Co. v. Watts, 1 Wheat. 279-290; Polk v. Wendell, 4 Cranch, 87-98; McKeen v. DeLaney, 5 ib. 22; Gardner v. Collins, 2 Peters, 85; United States v. Morrison, 4 Peters, 124; Catheart v. Robinson, 5 Peters, 264; Green v. Neal, 6 Peters, 291; Walker v. Forbes, at the last term; Davidson v. Sharp, 6 Iredell, 14; Inge v. Murphy, 10 Ala. 885 ; Peake v. Yeldell, 17 Ala. 136; Hanrick v. Andrews, 9 Porter, 9; American P. W. v. Lawrence, 3 Zabriskie, 590.
*590An examination of the facts in the eases above cited will show, that the courts have not denied the authority of decisions construing statutes, either because the decisions were made after the transactions which were passed upon occurred, or after the persons affected had emigrated to another State. The principle is, that by the comitas gen-tium the courts of the several States must be permitted to construe their own statutes; and it is founded in justice and reason. The courts of each State must be presumed best to understand all the circumstances which influence the judicial construction of its statutes.
The Maryland decision does not place an absurd or unreasonable construction upon the statute. The statute is “darkly and clumsily penned.” — Thrift v. Hannah, supra. Its meaning is doubtful. It is one of those laws, which different minds might differently understand. This case, therefore, does not present an example of an unreasonable and absurd construction placed by the court of a State upon its statute; and we are not called upon to decide, and therefore do not decide, what weight should be allowed to such a decision.
From the decision which we have made upon the main question in this .case it follows, that the petitioners are not free persons, unless the defendant is estopped by the judgment of the Kentucky court, in favor of the freedom of their maternal ancestor. Let it be conceded, as the evidence conduces to show, that the defendant here holds under Molly Townsend, who was the defendant in the Kentucky suit; and that the title was derived from her after the judgment in that suit; and the question, thus presented in the most favorable aspect for the petitioners, we are constrained to decide against them. If Molly Townsend herself were'the defendant to this suit, she would not be estopped by the judgment. Estoppels must operate reciprocally. Molly Townsend would not be estopped, as to the question of the freedom of the child, by a judgment in favor of tire mother, unless the child would have been estopped, if the judgment had been the other way. A judgment against a vendor or assignor, after the title has passed to the vendee or assignee, does *591not operate as an estoppel against tbe latter.. A foreclosure of a mortgage, in a suit against tbe mortgagor, does not operate against an assignee of tbe mortgagor by a previous assignment. — Crutchfield v. Hudson, 23 Ala. 303; Thomason v. Odum, at tbe last term; Cooper v. Martin, 1 Dana, 23; Starkie on Ev. 2 Part, 194; Adams v. Barnes, 17 Mass. 365; 3 Bacon’s Abr. 549, Evidence, F; The same principle is applicable here. Grasey, who is tbe mother of tbe other petitioners, bad derived freedom or slavery by birth from her mother, Matilda, before tbe proceedings were instituted in tbe Kentucky court; and her right to freedom could not be affected by a judgment against her mother in that ease. As G-rasey would not have been estopped by tbe judgment in that case, if adverse to her mother, so she cannot avail herself of tbe contrary judgment as an estoppel in her favor.
We are aware that tbe decision in tbe case of Shelton v. Barber, 2 Wash. “82, is susceptible of .a construction which would place it 'in opposition to tbe conclusion -above expressed; but we think we are sustained by principle, and we regard tbe decisions in Davis v. Wood, 1 Wheaton, 1; Davis v. Wood, 7 Cranch, 271; and Alexander v. Stakely, 7 S. & R. 299, as inconsistent with Shelton v. Barber, supra, and supporting the proposition we have laid down.
It results from what we have said, that, upon the facts before us, the petitioners are slaves. It is therefore unnecessary for us to consider the other questions argued.
The judgment of the court below is reversed, and the «cause remanded.