If the common law have the force of a statutory enactment in Missouri, it is clear, as it seems to me, that a slave who, by a residence in Illinois in the service of his master, becomes entitled to his freedom, cannot again be reduced to slavery by returning to his former domicil in a slave State. It is unnecessary to say what legislative power might do by a general act in such a case, but it would be singular if a freeman could be made a slave by the exercise of a judicial discretion. And it would be still more extraordinary if this could be done, not only in the absence of special legislation, but in a State where the common law is in force. It is supposed by some, that the third article in the treaty of cession of Louisiana to this country, by France, in 1803, may have some bearing on this question. The article referred to provides, "that the inhabitants of the ceded territory shall be incorporated into the Union, and enjoy all the advantages of citizens of the United States, and in the mean time they shall be maintained and protected in the free enjoyment of their liberty, property, and the religion they profess." As slavery existed in Louisiana at the time of the cession, it is supposed this is a guaranty that there should be no change in its condition. The answer to this is, in the first place, that such a subject does not belong to the treaty-making power; and any such arrangement would have been nugatory. And, in the second place, by no admissible construction can the guaranty be carried further than the protection of property in slaves at that time in the ceded territory. And this has been complied with. The organization of the slave States of Louisiana, Missouri, and Arkansas, embraced every slave in Louisiana at the time of the cession. This removes every ground of objection under the treaty. There is therefore no pretence, growing out of the treaty, that any part of the territory of Louisiana, as ceded, beyond the organized States, is slave territory. Under the fifth head, we were to consider whether the status of slavery attached to the plaintiff and wife, on their return to Missouri. This doctrine is not asserted in the late opinion of the Supreme Court of Missouri, and up to 1852 the contrary doctrine was uniformly maintained by that court. In its late decision, the court say that it will not give effect in Missouri to the laws of Illinois, or the law of Congress called the Missouri compromise. This was the effect of the decision, though its terms were, that the court would not take notice, judicially, of those laws. In 1851, the Court of Appeals of South Carolina recognised the principle, that a slave, being taken to a free State, became free. (Commonwealth _v._ Pleasants, 10 Leigh Rep., 697.) In Betty _v._ Horton, the Court of Appeals held that the freedom of the slave was acquired by the action of the laws of Massachusetts, by the said slave being taken there. (5 Leigh Rep., 615.)