Such revocation would be contrary to the obligations of good faith, which enjoins the observance of our engagements; it would be repugnant to the principles on which government itself is founded; sovereignty in every lawful government is a limited power, and can do only what it is lawful to do.  Sovereigns, like individuals, are bound by their engagements, and have no moral power to break them.  Treaties between nations repose on this principle.  If the new State can revoke and annul an article concluded between itself and the United States, by which slavery is excluded from it, it may revoke and annul any other article of the compact; it may, for example, annul the article respecting public lands, and in virtue of its sovereignty, assume the right to tax and to sell the lands of the United States.  There is yet a more satisfactory answer to this objection.  The judicial power of the United States is co-extensive with their legislative power, and every question arising under the Constitution or laws of the United States, is recognizable by the judiciary thereof.  Should the new State rescind any of the articles of compact contained in the act of admission into the Union, that, for example, by which slavery is excluded, and should pass a law authorizing slavery, the judiciary of the United States on proper application, would immediately deliver from bondage, any person retained as a slave in said State.  And, in like manner, in all instances affecting individuals, the judiciary might be employed to defeat every attempt to violate the Constitution and laws of the United States.

If Congress possess the power to exclude slavery from Missouri, it still remains to be shown that they ought to do so.  The examination of this branch of the subject, for obvious reasons, is attended with peculiar difficulty, and cannot be made without passing over arguments which, to some of us, might appear to be decisive, but the use of which, in this place, would call up feelings, the influence of which would disturb, if not defeat, the impartial consideration of the subject.

Slavery, unhappily, exists within the United States.  Enlightened men, in the States where it is permitted, and everywhere out of them, regret its existence among us, and seek for the means of limiting and of mitigating it.  The first introduction of slaves is not imputable to the present generation, nor even to their ancestors.  Before the year 1642, the trade and ports of the colonies were open to foreigners equally as those of the mother country; and as early as 1620, a few years only after the planting of the colony of Virginia, and the same year in which the first settlement was made in the old colony of Plymouth, a cargo of negroes was brought into and sold as slaves in Virginia by a foreign ship.  From this beginning, the importation of slaves was continued for nearly two centuries.  To her honor, Virginia, while a colony, opposed the importation of slaves, and was the first State to prohibit the same, by a law passed for this purpose in 1778, thirty years before the general prohibition enacted by Congress in 1808.  The laws and customs of the States in which slavery has existed for so long a period, must have had their influence on the opinions and habits of the citizens, which ought not to be disregarded on the present occasion.