We are at a loss to understand upon what principle of law, applicable to appellate jurisdiction, it can be supposed that this court has not judicial authority to correct the last-mentioned error, because they had before corrected the former; or by what process of reasoning it can be made out, that the error of an inferior court in actually pronouncing judgment for one of the parties, in a case in which it had no jurisdiction, cannot be looked into or corrected by this court, because we have decided a similar question presented in the pleadings. The last point is distinctly presented by the facts contained in the plaintiff's own bill of exceptions, which he himself brings here by this writ of error. It was the point which chiefly occupied the attention of the counsel on both sides in the argument—and the judgment which this court must render upon both errors is precisely the same. It must, in each of them, exercise jurisdiction over the judgment, and reverse it for the errors committed by the court below; and issue a mandate to the Circuit Court to conform its judgment to the opinion pronounced by this court, by dismissing the case for want of jurisdiction in the Circuit Court. This is the constant and invariable practice of this court, where it reverses a judgment for want of jurisdiction in the Circuit Court.

It can scarcely be necessary to pursue such a question further. The want of jurisdiction in the court below may appear on the record without any plea in abatement. This is familiarly the case where a court of chancery has exercised jurisdiction in a case where the plaintiff had a plain and adequate remedy at law, and it so appears by the transcript when brought here by appeal. So also where it appears that a court of admiralty has exercised jurisdiction in a case belonging exclusively to a court of common law. In these cases there is no plea in abatement. And for the same reason, and upon the same principles, where the defect of jurisdiction is patent on the record, this court is bound to reverse the judgment, although the defendant has not pleaded in abatement to the jurisdiction of the inferior court.

The cases of Jackson v. Ashton and of Capron v. Van Noorden, to which we have referred in a previous part of this opinion, are directly in point. In the last-mentioned case, Capron brought an action against Van Noorden in a Circuit Court of the United States, without showing, by the usual averments of citizenship, that the court had jurisdiction. There was no plea in abatement put in, and the parties went to trial upon the merits. The court gave judgment in favor of the defendant with costs. The plaintiff thereupon brought his writ of error, and this court reversed the judgment given in favor of the defendant, and remanded the case with directions to dismiss it, because it did not appear by the transcript that the Circuit Court had jurisdiction.

The case before us still more strongly imposes upon this court the duty of examining whether the court below has not committed an error, in taking jurisdiction and giving a judgment for costs in favor of the defendant; for in Capron v. Van Noorden the judgment was reversed, because it did not appear that the parties were citizens of different States. They might or might not be. But in this case it does appear that the plaintiff was born a slave; and if the facts upon which he relies have not made him free, then it appears affirmatively on the record that he is not a citizen, and consequently his suit against Sandford was not a suit between citizens of different States, and the court had no authority to pass any judgment between the parties. The suit ought, in this view of it, to have been dismissed by the Circuit Court, and its judgment in favor of Sandford is erroneous, and must be reversed.

It is true that the result either way, by dismissal or by a judgment for the defendant, makes very little, if any, difference in a pecuniary or personal point of view to either party. But the fact that the result would be very nearly the same to the parties in either form of judgment, would not justify this court in sanctioning an error in the judgment which is patent on the record, and which, if sanctioned, might be drawn into precedent, and lead to serious mischief and injustice in some future suit.

We proceed, therefore, to inquire whether the facts relied on by the plaintiff entitled him to his freedom.

The case, as he himself states it, on the record brought here by his writ of error, is this:

The plaintiff was a negro slave, belonging to Dr. Emerson, who was a surgeon in the army of the United States. In the year 1834, he took the plaintiff from the State of Missouri to the military post at Rock Island, in the State of Illinois, and held him there as a slave until the month of April or May, 1836. At the time last-mentioned, said Dr. Emerson removed the plaintiff from said miltary post at Rock Island to the military post at Fort Snelling, situate on the west bank of the Mississippi river, in the territory known as Upper Louisiana, acquired by the United States of France, and situate north of the latitude of thirty-six degrees thirty minutes north, and north of the State of Missouri. Said Dr. Emerson held the plaintiff in slavery at said Fort Sneling, from said last-mentioned date until the year 1838.

In the year 1835, Harriet, who is named in the second count of the plaintiff's declaration, was the negro slave of Major Taliaferro, who belonged to the army of the United States. In that year, 1835, said Major Taliaferro took said Harriet to said Fort Snelling, a military post, situated as hereinbefore stated, and kept her there as a slave until the year 1836, and then sold and delivered her as a slave, at said Fort Snelling, unto the said Dr. Emerson hereinbefore named. Said Dr. Emerson held said Harriet in slavery at said Fort Snelling until the year 1838.

In the year 1836, the plaintiff and Harriet intermarried, at Fort Snelling, with the consent of Dr. Emerson, who then claimed to be their master and owner. Eliza and Lizzie, named in the third count of the plaintiff's declaration, are the fruit of that marriage. Eliza is about fourteen years old, and was born on board the steamboat Gipsey, north of the north line of the State of Missouri, and upon the river Mississippi. Lizzie is about seven years old, and was born in the State of Missouri, at the military post called Jefferson Barracks.