at once take his writ of error, and have the ruling reviewed here; while, if the same plea were ruled against the defendant, he must not only wait for a final judgment, but could in no event have the ruling of the Circuit Court upon the plea reviewed by this court. I know of no ground for saying that the laws of the United States have thus discriminated between the parties to a suit in its courts. It is further objected, that as the judgment of the Circuit Court was in favor of the defendant, and the writ of error in this cause was sued out by the plaintiff, the defendant is not in a condition to assign any error in the record, and therefore this court is precluded from considering the question whether the Circuit Court had jurisdiction. The practice of this court does not require a technical assignment of errors. (See the rule.) Upon a writ of error, the whole record is open for inspection; and if any error be found in it, the judgment is reversed. (Bank of U.S. _v._ Smith, 11 Wheat., 171.) It is true, as a general rule, that the court will not allow a party to rely on anything as cause for reversing a judgment, which was for his advantage. In this, we follow an ancient rule of the common law. But so careful was that law of the preservation of the course of its courts, that it made an exception out of that general rule, and allowed a party to assign for error that which was for his advantage, if it were a departure by the court itself from its settled course of procedure. The cases on this subject are collected in Bac. Ab., Error H. 4. And this court followed this practice in Capron _v._ Van Noorden, (2 Cranch, 126,) where the plaintiff below procured the reversal of a judgment for the defendant, on the ground that the plaintiff's allegations of citizenship had not shown jurisdiction.