The courts of a State have the same right, except that it is not final. This the original Judiciary Act of 1789 (Sec. 25) fully recognized. Something like it may belong to a Convention of the whole people of a State, called to act upon its fundamental concerns; for that would represent the sovereignty of the State as a whole in the fullest manner. It was from such a convention that the nullifying ordinance of 1832 proceeded, but the vice of its action was, not so much that it pronounced the protective tariff Acts unconstitutional and void, but that it assumed to deny any right of appeal in litigation growing out of these Acts and the Ordinance of Nullification, from the courts of South Carolina to the courts of the United States. This liberty of appeal in the regular course of judicial procedure is the one thing which keeps the United States in existence.
The law governing the ordinary transactions of life is that of the State where they may have their seat. This was affirmed in the original Judiciary Act,[Footnote: U. S. Revised Statutes, § 721. As "equity follows the law," State legislation creating new equitable rights or varying those formerly established also affects causes in equity in the Federal courts. Brine _v._ Insurance Co., 96 U. S. Reports, 627; but see James _v._ Gray, 131 Federal Reporter, 401.] as a general rule for the courts of the United States in trials at common law. By another Act of Congress,[Footnote: _Ibid_., § 914.] the practice, pleadings, and form and mode of proceeding in civil causes, other than those of equity and admiralty jurisdiction, in the Circuit and District Courts are to conform as nearly as may be to that followed in the State within which these courts may be held.
The State laws which are thus made a rule for the United States courts are the law of the State as it is understood and applied in its own courts. Hence the construction of a State statute, or the doctrines of the common law in a particular State, if definitely settled by the courts of that State, must be followed in subsequent litigation in the federal courts. Where, however, a State court has taken a certain position as to what the law is, and afterwards changes its position, the federal courts are not compelled to change with it, if this would do injustice to one who has meanwhile acted on the faith of the original ruling.[Footnote: Burgess _v._ Seligman, 107 U. S. Reports, 20, and see argument of Daniel Webster in Groves _v._ Slaughter, 15 Peters' Reports, 449, 489.]