But, under the act of 1875, the trial court is not bound by the pleadings of the parties, but may, of its own motion, if led to believe, that its jurisdiction is not properly invoked, inquire into the facts as they really exist.
Williams v. Nottawa, 104 U. S. 209;
Barry v. Edmunds, 116 U. S. 550;
Morris v. Gilmer, 129 U. S. 315;
Deputron v.
Young, 134 U. S. 241. And our present problem is to preserve as well the power of the trial court to make such inquiries as the right of suitors, so '"expressly reserved to them in the statutes, to have the action of the lower court reviewed by the Supreme Court of the United States.
In equity cases, which come up on appeal, and- where the evidence on which the court belotv acted is presented here, the action of that, court can be réadily reviewed. But in. cases at law, like the present one, how can we review the judgment of the. court below, unless that judgment is either based on the verdict of a. jury or upon facts found in an agreed statement?
The statute does not presents any particular mode in which the question of the jurisdiction is to be brought to the. attention of the court, nor how such question, when raised, shall be determined.
When such a question arises in an action at law its decision would usually depend upon matters of fact, and also usually involves a denial of formal/ but necessary, allegations contained in the plaintiff’s declaration or complaint. Such a case would be presented when the plaintiff’s allegation that the controversy was between citizens of different States, or when, as in the present case the allegation that the matter in dispute was of sufficient value to give the court jurisdiction, was denied.
In such cases, whether the question was raised by the defendant or. by the court on its own motion, the court might doubtless order the issue to be tried by the jury. The action of the court, in the admission or rejection of evidence, or in instructing the .jury, would thus be subjected to the review by this court which was intended by Congress.
Sue/ was the course pursued in the case of Jones v. League,