Louisiana was a province where slavery was not only lawful, but where property in slaves was the most valuable of all personal property. The province was ceded as a unit, with an equal right pertaining to all its inhabitants, in every part thereof, to own slaves. It was, to a great extent, a vacant country, having in it few civilized inhabitants. No one portion of the colony, of a proper size for a State of the Union had a sufficient number of inhabitants to claim admission into the Union. To enable the United States to fulfil the treaty, additional population was indispensable, and obviously desired with anxiety by both sides, so that the whole country should, as soon as possible, become States of the Union. And for this contemplated future population, the treaty as expressly provided as it did for the inhabitants residing in the province when the treaty was made. All these were to be protected "_in the mean time_;" that is to say, at all times, between the date of the treaty and the time when the portion of the Territory where the inhabitants resided was admitted into the Union as a State. At the date of the treaty, each inhabitant had the right to the _free_ enjoyment of his property, alike with his liberty and his religion, in every part of Louisiana; the province then being one country, he might go everywhere in it, and carry his liberty, property, and religion, with him, and in which he was to be maintained and protected, until he became a citizen of a State of the Union of the United States. This cannot be denied to the original inhabitants and their descendants. And, if it be true that immigrants were equally protected, it must follow that they can also stand on the treaty. The settled doctrine in the State courts of Louisiana is, that a French subject coming to the Orleans Territory, after the treaty of 1803 was made, and before Louisiana was admitted into the Union, and being an inhabitant at the time of the admission, became a citizen of the United States by that act; that he was one of the inhabitants contemplated by the third article of the treaty, which referred to all the inhabitants embraced within the new State on its admission. That this is the true construction, I have no doubt. If power existed to draw a line at thirty-six degrees thirty minutes north, so Congress had equal power to draw the line on the thirtieth degree--that is, due west from the city of New Orleans--and to declare that north of _that line_ slavery should never exist. Suppose this had been done before 1812, when Louisiana came into the Union, and the question of infraction of the treaty had then been presented on the present assumption of power to prohibit slavery, who doubts what the decision of this court would have been on such an act of Congress; yet, the difference between the supposed line, and that on thirty-six degrees thirty minutes north, is only in the degree of grossness presented by the lower line.