It has been argued that, if a colored person be made a citizen of a State, he cannot sue in the Federal court. The Constitution declares that Federal jurisdiction "may be exercised between citizens of different States," and the same is provided in the act of 1789. The above argument is properly met by saying that the Constitution was intended to be a practical instrument; and where its language is too plain to be misunderstood, the argument ends. In Chirae _v._ Chirae, (2 Wheat., 261; 4 Curtis, 99,) this court says: "That the power of naturalization is exclusively in Congress does not seem to be, and certainly ought not to be, controverted." No person can legally be made a citizen of a State, and consequently a citizen of the United States, of foreign birth, unless he be naturalized under the acts of Congress. Congress has power "to establish a uniform rule of naturalization." It is a power which belongs exclusively to Congress, as intimately connected with our Federal relations. A State may authorize foreigners to hold real estate within its jurisdiction, but it has no power to naturalize foreigners, and give them the rights of citizens. Such a right is opposed to the acts of Congress on the subject of naturalization, and subversive of the Federal powers. I regret that any countenance should be given from this bench to a practice like this in some of the States, which has no warrant in the Constitution. In the argument, it was said that a colored citizen would not be an agreeable member of society. This is more a matter of taste than of law. Several of the States have admitted persons of color to the right of suffrage, and in this view have recognised them as citizens; and this has been done in the slave as well as the free States. On the question of citizenship, it must be admitted that we have not been very fastidious. Under the late treaty with Mexico, we have made citizens of all grades, combinations, and colors. The same was done in the admission of Louisiana and Florida. No one ever doubted, and no court ever held, that the people of these Territories did not become citizens under the treaty. They have exercised all the rights of citizens, without being naturalized under the acts of Congress. There are several important principles involved in this case, which have been argued, and which may be considered under the following heads: 1. The locality of slavery, as settled by this court and the courts of the States. 2. The relation which the Federal Government bears to slavery in the States. 3. The power of Congress to establish Territorial Governments, and to prohibit the introduction of slavery therein. 4. The effect of taking slaves into a new State or Territory, and so holding them, where slavery is prohibited. 5. Whether the return of a slave under the control of his master, after being entitled to his freedom, reduces him to his former condition.