It is clear that the ordinance did not go into operation by virtue of the authority of the Confederation, but by reason of its modification and adoption by Congress under the Constitution. It seems to be supposed, in the opinion of the court, that the articles of cession placed it on a different footing from territories subsequently acquired. I am unable to perceive the force of this distinction. That the ordinance was intended for the government of the Northwestern Territory, and was limited to such Territory, is admitted. It was extended to Southern Territories, with modifications, by acts of Congress, and to some Northern Territories. But the ordinance was made valid by the act of Congress, and without such act could have been of no force. It rested for its validity on the act of Congress, the same, in my opinion, as the Missouri compromise line. If Congress may establish a Territorial Government in the exercise of its discretion, it is a clear principle that a court cannot control that discretion. This being the case, I do not see on what ground the act is held to be void. It did not purport to forfeit property, or take it for public purposes. It only prohibited slavery; in doing which, it followed the ordinance of 1787. I will now consider the fourth head, which is: "The effect of taking slaves into a State or Territory, and so holding them, where slavery is prohibited." If the principle laid down in the case of Prigg _v._ The State of Pennsylvania is to be maintained, and it is certainly to be maintained until overruled, as the law of this court, there can be no difficulty on this point. In that case, the court says: "The state of slavery is deemed to be a mere municipal regulation, founded upon and limited to the range of the territorial laws." If this be so, slavery can exist nowhere except under the authority of law, founded on usage having the force of law, or by statutory recognition. And the court further says: "It is manifest, from this consideration, that if the Constitution had not contained the clause requiring the rendition of fugitives from labor, every non-slaveholding State in the Union would have been at liberty to have declared free all runaway slaves coming within its limits, and to have given them entire immunity and protection against the claims of their masters."