If, however, the fact of citizenship is averred in the declaration, and the defendant does not deny it, and put it in issue by plea in abatement, he cannot offer evidence at the trial to disprove it, and consequently cannot avail himself of the objection in the appellate court, unless the defect should be apparent in some other part of the record. For if there is no plea in abatement, and the want of jurisdiction does not appear in any other part of the transcript brought up by the writ of error, the undisputed averment of citizenship in the declaration must be taken in this court to be true. In this case, the citizenship is averred, but it is denied by the defendant in the manner required by the rules of pleading; and the fact upon which the denial is based is admitted by the demurrer. And, if the plea and demurrer, and judgment of the court below upon it, are before us upon this record, the question to be decided is, whether the facts stated in the plea are sufficient to show that the plaintiff is not entitled to sue as a citizen in a court of the United States. We think they are before us. The plea in abatement and the judgment of the court upon it, are a part of the judicial proceedings in the Circuit Court, and are there recorded as such; and a writ of error always brings up to the superior court the whole record of the proceedings in the court below. And in the case of the United States _v._ Smith, (11 Wheat., 172,) this court said, that the case being brought up by writ of error, the whole record was under the consideration of this court. And this being the case in the present instance, the plea in abatement is necessarily under consideration; and it becomes, therefore, our duty to decide whether the facts stated in the plea are or are not sufficient to show that the plaintiff is not entitled to sue as a citizen in a court of the United States. This is certainly a very serious question, and one that now for the first time has been brought for decision before this court. But it is brought here by those who have a right to bring it, and it is our duty to meet it and decide it. The question is simply this: Can a negro, whose ancestors were imported into this country, and sold as slaves, become a member of the political community formed and brought into existence by the Constitution of the United States, and as such become entitled to all the rights, and privileges, and immunities, guarantied by that instrument to the citizen? One of which rights is the privilege of suing in a court of the United States in the cases specified in the Constitution.