Third. The chief territory which the United States acquired between the Revolution and the Mexican war, was Louisiana. This vast region was gained by treaty from France in 1803. It was then a single province and government of the French Republick, and was, through all its extent, a slaveholding country. In the third article of the treaty for its purchase, between the United States and the First Consul, it was stipulated that until the ceded territory should be incorporated, as States, in the Union, all its citizens should be "in the mean time maintained and protected in the free enjoyment of their liberty, property, and the religion which they profess." The settled doctrine of the courts of Louisiana has always been, that this guarantee covered all the citizens emigrating into any part of the territory before its erection into a State, as fully as those living in Louisiana in 1803.[58] Thus, the rights of slave owners in the whole of the Louisiana purchase were guaranteed to them by treaty, until such time as the part they inhabited became a sovereign State, and thus assumed plenary power over the subject. But, by Article 6th, § 2d, of the Constitution of the United States, all treaties made by the authority of the United States are declared to be the supreme law of the land. Thus the rights of the master in all this region were placed above the power of the legislature itself. [Footnote 58: Justice Catron, 19th Howard, p. 131.] Fourth. The federal constitution recognized and protected property in slaves, in every way which was competent to a federative compact of this kind. The slaveholding States had representation for three-fifths of their slaves. The slaves were made subjects of direct taxation, as property. The constitution provided expressly for a fugitive slave law, which was soon passed by the Congress, and continued to be the law of the land until the termination of the government. By the constitution, property in slaves was created like any other property; and no ground can be found for the assertion that its rights were more restricted than rights in cattle or lands. But the fundamental idea of that instrument was the impartial equality of all the citizens before the law. Whatever authority Congress had over the common territories, was as trustee for all the citizens of the United States equally. Hence it seems obvious that this body was bound to recognize in all the citizens equal rights, in going into those territories with any species of property which they might hold by the laws of any State, or of Congress, and to protect them in those rights while the country was in a territorial condition.